使用asp panel 设置隐藏和显示不起作用〉？

 前台：<asp:Panel ID="Panel1" runat="server" BorderWidth="0px" Visible="False" Width="100%">  
             www 
             </asp:Panel >   
点击按钮    想让这个层显示
  
 protected void Duty_gv_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            ImageButton TempIB_Mod = (ImageButton)e.Row.FindControl("lb_mod");
            TempIB_Mod.CommandName = "Duty_Mod";
            TempIB_Mod.CommandArgument = e.Row.RowIndex.ToString();
         
后台 
:
  protected void Duty_gv_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        int index = Convert.ToInt32(e.CommandArgument.ToString());
        GridViewRow GvRow = Duty_gv.Rows[index];
        SqlCommand cmd = DbClass.getCMD();
        switch (e.CommandName)
        { case "Duty_Mod":
                try
                {
              this.Panel1.Visible = true;
值可以传过来,但层就是不显示