whenever a node is clicked it expands but it scrolls to top .. it points to root node rather the node that is clicked

<asp:UpdatePanel runat="server" ID="UpdatePanel2">
    <contenttemplate>
        <asp:TextBox SkinID="txt210" ID="txtFilterLocation" Style="cursor: pointer" runat="server"
            meta:resourcekey="txtFilterLocationResource1">
        <asp:Button Width="0px" Height="0px" ID="btnFilterLocation" runat="server" Style="display: none;"
            meta:resourcekey="btnFilterLocationResource1" />
        <asp:ImageButton TabIndex="2" ID="imgFilterLocation" ClientIDMode="Static" ToolTip="Select Location"
            ImageUrl="~/App_Themes/Blue/Images/search_button_02.png" ImageAlign="Middle"
            Style="margin-left: 3px; border: none 0px" runat="server" OnClick="imgFilterLocation_Click"
            meta:resourcekey="imgFilterLocationResource1" />
        <asp:ModalPopupExtender OnOkScript="CheckChecked();" ClientIDMode="Static" TargetControlID="btnFilterLocation"
            BackgroundCssClass="modalBackground" ID="ModalPopupExtender2" runat="server"
            PopupControlID="pnlFilterLocation" RepositionMode="RepositionOnWindowScroll"
            ViewStateMode="Enabled" DynamicServicePath="" Enabled="True">        
        <asp:Panel ID="pnlFilterLocation" style="display:none;"  runat="server" ScrollBars="Auto" BorderStyle="Solid"
            BorderWidth="1px" BorderColor="Navy" BackColor="White" meta:resourcekey="pnlFilterLocationResource1">
            <table cellpadding="1" cellspacing="0" width="600px">
                <tr>
                    <td align="left" valign="top">
                        <asp:Label ID="Label10" runat="server" Text="Locations"  Style="color:Black;" meta:resourcekey="Label10Resource1">
                    </td>
                </tr>
                <tr class="sample2">
                    <td align="center" valign="top">
                        <div style="overflow: auto; height: 290px; width: 95%; text-align: left;" id="tvDIV">
                        <asp:UpdatePanel runat="server" ID="UpdatePanel1">
    <contenttemplate>
                            <asp:TreeView ID="tvFilterLocation" runat="server" OnSelectedNodeChanged="tvFilterLocation_SelectedNodeChanged" 
                                meta:resourcekey="tvFilterLocationResource1" AutoScroll="false" 
                                ontreenodeexpanded="tvFilterLocation_TreeNodeExpanded" PopulateNodesFromClient="False" 
                                ontreenodecollapsed="tvFilterLocation_TreeNodeCollapsed" >
                            
                            </contenttemplate>
                        </div>
                    </td>
                </tr>
                <tr class="sample2">
                    <td align="right" valign="top">
                        <asp:Button ID="Button3" Style="display: none;" runat="server" Text="Select" meta:resourcekey="Button3Resource1" /><asp:Button
                            ID="Button4" runat="server" Text="Cancel" meta:resourcekey="Button4Resource1" />
                    </td>
                </tr>
            </table>
        
    </contenttemplate>
    <triggers>
            <asp:PostBackTrigger  ControlID="tvFilterLocation" />
        </triggers>