asp.net radiobuttonlist doesnt fire on selection

Question

I have created a simple radiobuttonlist. And I wrote simple function to do something on selection

here is the radiobuttonlist

<asp:RadioButtonList  ID="payment_type" CssClass="rbl_type" runat="server" TextAlign="Right" RepeatDirection="Horizontal" BorderStyle="None" OnSelectedIndexChanged="payment_type_SelectedIndexChanged">
      <asp:ListItem Value="0">Serbest Ödeme</asp:ListItem>
      <asp:ListItem Value="1">Ön Tanımlı Ödeme</asp:ListItem>
</asp:RadioButtonList>

here is the c# code

protected void payment_type_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (payment_type.SelectedValue == "0")
        {
            pnl_serbest.Visible = true;
            pnl_on_tanimli.Visible = false;
        }
        else
        {
            pnl_serbest.Visible = false; 
            pnl_on_tanimli.Visible = true;
        }
    }

but it doesnt trigger anything. what am I doing wrong?

Answer 1

Add

AutoPostBack="true"  

attribute to your <asp:RadioButtonList /> tag.