RadioButtonList OnSelectedIndexChanged仅触发一次

Question

I have a radiobuttonlist that is hardcoded into my asp.net page like so:

<asp:RadioButtonList runat="server" ID="rblOrientation" RepeatDirection="Horizontal"
    OnSelectedIndexChanged="rblOrientation_onSelectedIndexChanged" AutoPostBack="true">
    <asp:ListItem Text="Portrait" Value="P" Selected="True"></asp:ListItem>
    <asp:ListItem Text="Landscape" Value="L"></asp:ListItem>
</asp:RadioButtonList>

The code behind is as follows:

protected void rblOrientation_onSelectedIndexChanged(object sender, EventArgs e)
{
    ddlPaperSize_onSelectedIndexChanged(sender, e);
}

Basically what happens is it calls on another function which updates a bunch of values that are within an update panel. This is also hardcoded in and looks like this:

<asp:UpdatePanel runat="server">
    <ContentTemplate>
        <asp:Label ID="lblPaperWidth" runat="server" />
        <span id="txtUOMWidth" runat="server" />&nbsp;×
        <asp:Label ID="lblPaperHeight" runat="server" />
        <span id="txtUOMHeight" runat="server" />
    </ContentTemplate>
    <Triggers>
        <asp:AsyncPostBackTrigger ControlID="rblOrientation" />
        <asp:AsyncPostBackTrigger ControlID="ddlPaperSize" />
        <asp:AsyncPostBackTrigger ControlID="ddlScale" />
    </Triggers>
</asp:UpdatePanel>

Everything works fine the first time I change the value of the radiobuttonlist, however, if I try a second time it does not work. Does anyone know why this might be? Any advice would be great, thanks!

note: From the testing I have done, this is the only control where the OnSelectedIndexChanged is not acting how I expected it to. The event for the rest of the controls fires correctly

Answer 1

Try this code, which works fine for me.

<asp:ScriptManager ID="smMain" runat="server" />

<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Always" ChildrenAsTriggers="true" >      
      <ContentTemplate>
        <asp:RadioButtonList runat="server" ID="rblOrientation" RepeatDirection="Horizontal"
             OnSelectedIndexChanged="rblOrientation_onSelectedIndexChanged" AutoPostBack="true">
         <asp:ListItem Text="Portrait" Value="P" Selected="True"></asp:ListItem>
         <asp:ListItem Text="Landscape" Value="L"></asp:ListItem>
        </asp:RadioButtonList>

      </ContentTemplate>
    </asp:UpdatePanel>