操作RadGrid1，RadAjaxLoadingPanel1不出现

操作RadGrid1并且有PostBack时，如果RadAjaxLoadingPanel1不出现，要检查以下设置是否正确：

<telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
           <AjaxSettings>
               <telerik:AjaxSetting AjaxControlID="RadAjaxManager1">
                   <UpdatedControls>
                       <telerik:AjaxUpdatedControl ControlID="RadGrid1" LoadingPanelID="RadAjaxLoadingPanel1" />
                   </UpdatedControls>
               </telerik:AjaxSetting>
           </AjaxSettings>
           <AjaxSettings>
               <telerik:AjaxSetting AjaxControlID="RadGrid1">
                   <UpdatedControls>
                       <telerik:AjaxUpdatedControl ControlID="RadGrid1" LoadingPanelID="RadAjaxLoadingPanel1" />
                   </UpdatedControls>
               </telerik:AjaxSetting>
           </AjaxSettings>
</telerik:RadAjaxManager>