Server side button onclick does not trigger with RadAjaxManager

[Jack]

I am using several settings in RadAjaxManager. I have a server control asp button which re-loads the whole page when clicked. To prevent that I put this setting in RadAjaxManager

     <telerik:AjaxSetting AjaxControlID="btnPrint">

        <UpdatedControls><telerik:AjaxUpdatedControl ControlID="btnPrint" />

      </UpdatedControls></telerik:AjaxSetting>

but for some reason my code behind click event does not fire. Any ideas please

    <asp:Button ID="btnPrint" runat="server" Text="Print" CssClass="button" OnClick="btnPrint_Click" ></asp:Button>