Update Panel is not working properly

Hello,

I am using visual studio 2008.

I am using update panel for partial page rendering.

But is refreshing whole page only.

Code is as below:

<div>
                                                    <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true">
                                                    </asp:ScriptManager>
                                                    <asp:UpdatePanel ID="UpdatePanel2" runat="server">
                                                        <ContentTemplate>
                                                            <asp:RadioButtonList ID="ChkBoxListAction" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ChkBoxListAction_SelectedIndexChanged">
                                                                <asp:ListItem Selected="True">EMail</asp:ListItem>
                                                                <asp:ListItem>SMS</asp:ListItem>
                                                                <asp:ListItem>NewsLetter</asp:ListItem>
                                                                <asp:ListItem>EMail-Template</asp:ListItem>
                                                                <asp:ListItem>SMS-Template</asp:ListItem>
                                                                <asp:ListItem>E-Books</asp:ListItem>
                                                            </asp:RadioButtonList>
                                                            <asp:CheckBox ID="chkprint" AutoPostBack="True" runat="server" Text="Print" />
                                                        </ContentTemplate>
                                                    </asp:UpdatePanel>
</div>