i already try to follow the code given.but it still doesnt appear as i want. when i click the radiobutton nothing happen.my code is same with the link.

blur.....

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">


<asp:Content ID="Content2" runat="server"
contentplaceholderid="ContentPlaceHolder1">
<form id="form1" runat="server">
<div class="post">
<div class="post-bgtop">
<div class="post-bgbtm">

Welcome to Operation Management Centre

<p class="title">
Please select category:</p>
<div class="entry">
<p>
 <asp:DropDownList ID="ddl1" runat="server">
<asp:ListItem>Please Select
<asp:ListItem>Signals & Communication Failure
<asp:ListItem>Failure
<asp:ListItem>Coach & Wagon Defect

<asp:Button ID="Button1" runat="server" onclick="Button1_Click1"
Text="Submit" />
</p>
<p>
<asp:RadioButtonList ID="RadioButtonList1" runat="server" OnSelectedIndexChanged = "RadioButtonList1_SelectedIndexChanged">

</p>
<p>
 <asp:Panel ID="Panel1" runat="server" Visible="False">
<table class="style1">
<tr>
<td class="style1">
<asp:Label ID="Label8" runat="server" Text="Origin:">
</td>
<td class="style1">
<asp:DropDownList ID="origin1_list" runat="server"
DataSourceID="SqlDataSource1" DataTextField="LCN_NAME"
DataValueField="LCN_NAME" AppendDataBoundItems="true">
<asp:ListItem>--Please Select--

<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:ConnectionString2 %>"
ProviderName="<%$ ConnectionStrings:ConnectionString2.ProviderName %>"
SelectCommand="SELECT "LCN_NAME" FROM "T_LOCATION"">


<asp:TextBox ID="origin1Text" runat="server" Visible="False">

</td>
</tr>
<tr>
<td class="style9">
<asp:Label ID="Label9" runat="server" Text="Destination:">
</td>
<td>
<asp:DropDownList ID="dest1_list" runat="server"
DataSourceID="SqlDataSource1" DataTextField="LCN_NAME"
DataValueField="LCN_NAME" AppendDataBoundItems="true">
<asp:ListItem>--Please Select--


<asp:TextBox ID="dest1Text" runat="server" Visible="False">


<br />

</td>
</tr>
<tr>
<td class="style9">
<asp:Label ID="Label3" runat="server" Text="Date:"></td>

i cannot copy all the source code.it eliminates some lines..

i already attached the code behind before..

i hope u understand the code.

thanx..

i change the properties of radiobuttonlist: autopostback to true.it works.it show the panel form that i want. but i must put 'if (RadioButtonList1.SelectedIndex == -1)' or else i get error out of index range.

but after the click the radiobutton dissapear whenever the panel is show..

here the code behind:
if (ddl1.SelectedIndex == 1)
{
RadioButtonList1.Visible = true;
ListItem[] item = new ListItem[2];
item[0] = new ListItem("KVDT & RIDT", "KVDT & RIDT");
RadioButtonList1.Items.Add(item[0]);
item[1] = new ListItem("Outside DT", "Outside DT");
RadioButtonList1.Items.Add(item[1]);

}
if (ddl1.SelectedIndex == 2)
{
RadioButtonList1.Visible = true;
ListItem[] item = new ListItem[2];
item[0] = new ListItem("ETS/EMU", "ETS/EMU");
RadioButtonList1.Items.Add(item[0]);
item[1] = new ListItem("Locomotive", "Locomotive");
RadioButtonList1.Items.Add(item[1]);
}

protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{

if (RadioButtonList1.SelectedIndex == -1)
{
RadioButtonList1.Visible = true;

Panel1.Visible = true;

}

if (RadioButtonList1.SelectedIndex == 0)
{
RadioButtonList1.Visible = true;
Panel1.Visible = true;
}

}