problem with radiobuttonlist in update panel

<asp:Panel ID="SelectAttributesPanel" runat="server" Width="230px" BackColor="#F0F8FF" BorderColor="Black" BorderWidth="1" Font-Names="Verdana" Font-Size="X-Small" >
 <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
 <ContentTemplate>
                                        <asp:RadioButtonList ID="rdbRemarks" runat="server" RepeatDirection="Horizontal"
AutoPostBack="True">
<asp:ListItem Value="F1">Accept</asp:ListItem>
<asp:ListItem Value="F1">Objection Clear</asp:ListItem>
<asp:ListItem Value="F4">Objection</asp:ListItem>
<asp:ListItem Value="R">Reject</asp:ListItem>
 </asp:RadioButtonList>
 </ContentTemplate>
 <Triggers>
 <asp:AsyncPostBackTrigger ControlID="rdbRemarks" EventName="SelectedIndexChanged" />
 </Triggers>
 </asp:UpdatePanel> </asp:Panel>