gridview里面自带的删除或修改 为什么我加了UpdatePanel  后就有时能触发有时又不能触发呢 
            代码如下：

                                <asp:UpdatePanel ID="UpdatePanel2" runat="server">
                                <ContentTemplate>
                               <asp:GridView ID="gvtra" runat="server" AutoGenerateColumns="False" Width="800px" onrowcancelingedit="gvtra_RowCancelingEdit" onrowdeleting="gvtra_RowDeleting" onrowediting="gvtra_RowEditing" onrowupdating="gvtra_RowUpdating">
                                   <Columns>
                                       <asp:BoundField DataField="START" HeaderText="开始时间" />
                                       <asp:BoundField DataField="ENDING" HeaderText="结束时间" />
                                       <asp:BoundField DataField="CONTENT" HeaderText="培训内容" />
                                       <asp:BoundField DataField="PLACE" HeaderText="培训地点" />
                                       <asp:BoundField DataField="CERTIFICATE" HeaderText="证书" />
                                       <asp:BoundField DataField="ID" HeaderText="ID" ReadOnly="True" />
                                       <asp:CommandField ShowDeleteButton="True" />
                                       <asp:CommandField ShowEditButton="True" />
                                   </Columns>
                               </asp:GridView>
                                </ContentTemplate>
                               </asp:UpdatePanel>