问一个关于DataGrid的问题！

cs:
private void DataGrid1_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
{
Panel cPnl=(Panel)e.Item.Cells[0].FindControl("SPanel");
cPnl.Visible=false;
}
html:
<asp:TemplateColumn>
   <ItemTemplate>
      <asp:Panel Runat="server" ID="CPanel">
<asp:Button runat="server" Text="查看" CommandName="select" ID="Button1"></asp:Button>
<asp:Button runat="server" Text="删除" CommandName="delete" ID="Button2"></asp:Button>
<asp:Button runat="server" Text="更新" CommandName="edit" ID="Button3"></asp:Button>
</asp:Panel>
<asp:Panel Runat="server" ID="SPanel">
<asp:Button runat="server" Text="确定" CommandName="Yes" ID="Button6"></asp:Button>
<asp:Button Runat="server" Text="取消" CommandName="Cancel" ID="Button7"></asp:Button>
</asp:Panel>
</ItemTemplate>
</asp:TemplateColumn>它会提示cPnl.Visible=false;这里产生错误！未将对象应用到实例！我在ItemCommand里使用sPanel是正常的