SelectedIndexChanged not working while RadioButtonList selected asp.net c#? autopostback also set to true?

Question

i've been struggling here for lot... kindly help.. below aspx page code...

<asp:RadioButtonList ID="sing_group" runat="server" RepeatDirection="Horizontal" 
                        onselectedindexchanged="sing_group_SelectedIndexChanged" AutoPostBack="true">
                        <asp:ListItem Value="0">Single</asp:ListItem>
                        <asp:ListItem Value="1">Group</asp:ListItem>
                    </asp:RadioButtonList>

my code behind code...

    protected void sing_group_SelectedIndexChanged(object sender, EventArgs e)
    {

        if (sing_group.SelectedValue == "0")
        {
            first_name.Enabled = true;
            last_name.Enabled = true;
            group_name.Enabled = false;
        }
        else
        {
            first_name.Enabled = false;
            last_name.Enabled = false;
            group_name.Enabled = true;
        }

    }

Answer 1

Try like this as well.. this will run for sure..

<asp:RadioButtonList ID="sing_group" runat="server" RepeatDirection="Horizontal" 
                       AutoPostBack="true">
                        <asp:ListItem Value="0">Single</asp:ListItem>
                        <asp:ListItem Value="1">Group</asp:ListItem>
                    </asp:RadioButtonList>

Protected Void Page_Load(Object Sender, EventArgs e){
    sing_group.SelectedIndexChanged += sing_group_SelectedIndexChanged;
}
protected void sing_group_SelectedIndexChanged(object sender, EventArgs e)
{

    if (sing_group.SelectedValue == "0")
    {
        first_name.Enabled = true;
        last_name.Enabled = true;
        group_name.Enabled = false;
    }
    else
    {
        first_name.Enabled = false;
        last_name.Enabled = false;
        group_name.Enabled = true;
    }

}

Answer 2

As per MSDN , the event name is OnSelectedIndexChanged In your code it is all in small case.

<asp:RadioButtonList id="RadioButtonList1" 
            OnSelectedIndexChanged="Index_Changed"
            AutoPostBack="true"
            runat="server"/>

Answer 3

You're writing wrong code. Please, change your code.

Your code is:

onselectedindexchanged="sing_group_SelectedIndexChanged"

But should be:

OnSelectedIndexChanged="sing_group_SelectedIndexChanged"

You can get output.