Update panel is not working in panel using ASP.NET

<div id="Tabs">
            <!-- Nav tabs -->
            <ul class="nav nav-tabs" style="font-size: 12px">
                <li style="width: 110px"><a href="#ScanGuest">Scan Guest</a></li>                <li style="width: 90px"><a href="#Reprint">Reprint</a></li>                <li style="width: 150px"><a href="#FlightWiseReport">Flight Wise Report</a></li>                <li style="width: 160px"><a href="#DateWiseReport">Date Wise Report</a></li>                <li style="width: 160px"><a href="#LoungeAccessReport">Lounge Access Report</a></li>                <li style="width: 120px"><asp:HyperLink runat="server" ID="hp" aria-controls="MainMenu" NavigateUrl="~/scan_demo.aspx" Text="Main Menu"></li>            </ul>



<div class="tab-pane" id="Reprint">
                      <asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional">
                        <contenttemplate>                            

                    
                        <table width="100%"><tbody><tr>                            <td valign="top">                                
                                   <table width="100%"><tbody><tr height="40">                                        <td style="padding-left: 30px" valign="top">                                            Report</td>                                    </tr>                                    <tr>                                        <td style="padding-top: 2%">                                            
                                                <table width="100%"><tbody><tr>                                                    <td width="30%" style="padding-left: 30px">                                                        <asp:Label ID="lblddate" runat="server" Font-Bold="True" Text="Date" CssClass="bold"></td>                                                    <td width="30%" style="padding-left: 30px">                                                        <asp:Label ID="lblCust" runat="server" CssClass="bold" Font-Bold="True" Text="Customer"></td>                                                    <td width="40%" style="padding-left: 30px">                                                        <asp:Label ID="lblFlightNo" runat="server" CssClass="bold" Text="Flight No."></td>                                                </tr>                                                <tr>                                                    <td width="30%" style="padding-left: 30px">                                                        <asp:DropDownList ID="DDLddate" Style="height: 40px; width: 80%; padding-left: 10px;" runat="server" CssClass="form-control" AutoPostBack="True" OnSelectedIndexChanged="DDLddate_SelectedIndexChanged">
                                                            <asp:ListItem Text="Select" Value="-1">
                                                        </td>                                                    <td width="30%" style="padding-left: 30px">                                                        <asp:DropDownList ID="DDLCust" Style="height: 40px; width: 80%; padding-left: 10px;" runat="server" CssClass="form-control" AutoPostBack="True" OnSelectedIndexChanged="DDLCust_SelectedIndexChanged">
                                                            <asp:ListItem Text="Select" Value="-1">
                                                        </td>                                                    <td width="40%" style="padding-left: 30px">                                                        <asp:DropDownList ID="ddlFlightNoSG" Style="height: 40px; width: 60%; padding-left: 10px;" runat="server" CssClass="form-control" AutoPostBack="True" OnSelectedIndexChanged="ddlFlightNoSG_SelectedIndexChanged">
                                                            <asp:ListItem Text="Select" Value="-1">
                                                        </td>                                                </tr>                                            </tbody></table>
                                        </td>                                    </tr>                                    <tr>                                        <td style="padding-left: 30px">                                            <div style="height: 310px">
                                                <asp:GridView ID="GRVCust" runat="server" AutoGenerateColumns="False" CellPadding="4" CssClass="form-control"
                                                    ForeColor="#333333" GridLines="Vertical" OnSelectedIndexChanged="GRVCust_SelectedIndexChanged">
                                                    <AlternatingRowStyle BackColor="White" />
                                                    <columns>
                                                        <asp:CommandField ShowSelectButton="True" />
                                                        <asp:BoundField DataField="Name" HeaderText="Name" />
                                                        <asp:BoundField DataField="FFPNo" HeaderText="FFP No." />
                                                        <asp:BoundField DataField="JPCard" HeaderText="JP Card" />
                                                        <asp:BoundField DataField="SeatNo" HeaderText="Seat No." />
                                                        <asp:BoundField DataField="Class" HeaderText="Class" />
                                                        <asp:BoundField DataField="SeqNo" HeaderText="Seq No." />
                                                        <asp:BoundField DataField="Source" HeaderText="Source" />
                                                        <asp:BoundField DataField="Dest" HeaderText="Dest" />
                                                        <asp:BoundField DataField="GuestOf" HeaderText="Guest Of" />
                                                    
                                                    <EditRowStyle BackColor="#2461BF" />
                                                    <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
                                                    <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
                                                    <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />
                                                    <RowStyle BackColor="#EFF3FB" />
                                                    <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
                                                
                                            </div>
                                        </td>                                    </tr>                                    <tr>                                        <td>                                            
                                                <table width="100%"><tbody><tr>                                                    <td width="30%" style="padding-left: 30px"><asp:Label ID="lblcount1" runat="server" Font-Bold="True" Text="Count" Width="63px" CssClass="bold"></td>                                                    <td width="30%" style="padding-left: 30px"><asp:TextBox ID="txtcount1" runat="server" ReadOnly="True" Width="76px"></td>                                                    <td width="40%"></td>                                                </tr>                                                <tr><td align="right" colspan="3"><asp:Button ID="Button3" runat="server" CssClass="button" Font-Bold="True" Height="35px" OnClick="btnPrint1_Click" Text="PRINT" Width="100px" /></td></tr>                                            </tbody></table>
                                         
                                        </td>                                    </tr>                                </tbody></table>

                            </td>                        </tr>                    </tbody></table>
             
                  
                        <triggers>
                            <asp:AsyncPostBackTrigger ControlID="DDLddate" EventName="SelectedIndexChanged" />
                            <asp:AsyncPostBackTrigger ControlID="DDLCust" EventName="SelectedIndexChanged" />
                            <asp:AsyncPostBackTrigger ControlID="ddlFlightNoSG" EventName="SelectedIndexChanged" />
                        
                    
                </div>
</div>


-------------------------------------------------------------
Cs code-------------------------------------------
on page load-----
 Page.Title = "Report";
                DDLDate.Attributes["onchange"] = "return IsDropDownIndexZero('" + DDLDate.ClientID + "')";
                ddlFlightNo.Attributes["onchange"] = "return IsDropDownIndexZero('" + ddlFlightNo.ClientID + "')";
                DDLddate.Attributes["onchange"] = "return IsDropDownIndexZero('" + DDLddate.ClientID + "')";
                DDLCust.Attributes["onchange"] = "return IsDropDownIndexZero('" + DDLCust.ClientID + "')";
                DDLDate1.Attributes["onchange"] = "return IsDropDownIndexZero('" + DDLDate1.ClientID + "')";
                DDLFlt.Attributes["onchange"] = "return IsDropDownIndexZero('" + DDLFlt.ClientID + "')";
                ddlByDate.Attributes["onchange"] = "return IsDropDownIndexZero('" + ddlByDate.ClientID + "')";

 protected void DDLddate_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                if (DDLddate.SelectedIndex > 0)
                {
                    GRVCust.DataSource = null;
                    GRVCust.DataBind();
                    ddlFlightNoSG.Items.Clear();
                    txtcount2.Text = "";
                    DDLCust.Items.Clear();
                    DDLCust.Items.Add("Select");
                    DDLCust.Items.Add("Self");
                    DDLCust.Items.Add("Guest");
                  
                }
                else
                {
                  
                }
            }
            catch (Exception ex)
            {
                ScriptManager.RegisterStartupScript(this.UpdatePanel2, typeof(string), "alertScript", "alert('" + ex.Message + "');", true);
            }
           
        }


 protected void DDLCust_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                if (DDLddate.SelectedIndex > 0)
                {
                    ddlFlightNoSG.Items.Clear();
                    GRVCust.DataSource = null;
                    GRVCust.DataBind();
                    txtcount2.Text = "";
                    string URL1 = "http://" + serverIP + "/loungejppl/fltinfo.aspx?flightdate=" + DDLddate.SelectedItem.ToString() + "&loc=" + Session["Location"].ToString();
                    //string URL1 = "http://" + serverIP + "/loungejppl/fltinfo.aspx?flightdate=" + DDLddate.SelectedItem.ToString() + "&loc=" + Session["Location"].ToString();
                    WebRequest request1 = WebRequest.Create(URL1);
                    WebResponse response1 = request1.GetResponse();
                    StreamReader reader1 = new StreamReader(response1.GetResponseStream());
                    string str1 = reader1.ReadLine();
                    response1.Close();
                    if (!String.IsNullOrEmpty(str1) && str1 != "No" && str1 != "SE")
                    {
                        str1 = str1.Trim();

                        string[] loc1 = str1.Split(new char[] { Convert.ToChar(3) }, StringSplitOptions.RemoveEmptyEntries);
                        ddlFlightNoSG.Items.Add("Select");
                        for (int i = 0; i < loc1.Length; i++)
                        {
                            ddlFlightNoSG.Items.Add(loc1[i].ToString());
                        }
                    }
                    else if (String.Compare(str1, "No", false) == 0)
                    {
                        ScriptManager.RegisterStartupScript(this.UpdatePanel1, typeof(string), "alertScript", "alert('No Info');", true);
                    }
                    else if (String.Compare(str1, "SE", false) == 0)
                    {
                        ScriptManager.RegisterStartupScript(this.UpdatePanel1, typeof(string), "alertScript", "alert('Server Connection Error..');", true);
                    }
                }
            }
            catch (Exception ex)
            {
                ScriptManager.RegisterStartupScript(this.UpdatePanel1, typeof(string), "alertScript", "alert('" + ex.Message + "');", true);
            }
        }

What I have tried:

above i post my code update panel is not working when i change dropdown value then page refresh and goes on first panel in ScanGuest so how to fix issues after refresh page should not be change

i am using javascript in master page when i remove javascript from master page then i works fine otherwise they not working fine


js function which is call on master page-

function DisableBackButton() {
    history.go(1);

}
function ScanClear(val1, val2, val3, val4, val5, val6, val7, val8, val9, val10, val11, val12, val13) {
    val1.value = ""; val2.value = ""; val3.value = ""; val4.value = ""; val5.value = ""; val6.value = ""; val7.value = ""; val8.value = ""; val9.value = ""; val10.value = ""; val11.value = ""; val12.value = ""; val13.value = "";
}
function UnScanClear(val1, val2, val3, val4, val5, val6, val7, val8, val9) {
    val1.value = ""; val2.value = ""; val3.value = ""; val4.value = ""; val5.value = ""; val6.value = ""; val7.value = ""; val8.value = ""; val9.value = "";
}
function Clear(val1, val2, val3, val4, val5, val6) {
    val1.value = ""; val2.value = ""; val3.value = ""; val4.value = "";
}
function ClearMessage(val1) {
    val1.innerText = "";
    //document.forms[0].submit();
}
function ClearComment(val1) {
    val1.innerText = "";
    return false;
}
function IsDropDownIndexZero(val1) {
    debugger;
    if (document.getElementById(val1).selectedIndex == 0) {
        return false;
    }
    document.forms[0].submit();
}

please help