.net页面调试时闪下就丢失，求助！！急
代码调试时，页面闪下就丢失了，直接上代码；[code=C#][/code]<%@ Page Language="C#" MasterPageFile="~/SampleManager/Sample.Master" AutoEventWireup="true" CodeBehind="CreateSampleOrder.aspx.cs" Inherits="Flag.Net.SampleManager.CreateSampleOrder" Title="Create Sample Order" %>

<%@ Register Assembly="DevExpress.Web.ASPxGridView.v9.3.Export, Version=9.3.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a"
  Namespace="DevExpress.Web.ASPxGridView.Export" TagPrefix="dx" %>

<%@ Register Assembly="DevExpress.Web.ASPxGridView.v9.3, Version=9.3.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a"
  Namespace="DevExpress.Web.ASPxGridView" TagPrefix="dx" %>
<%@ Register Assembly="DevExpress.Web.ASPxEditors.v9.3, Version=9.3.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a"
  Namespace="DevExpress.Web.ASPxEditors" TagPrefix="dx" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">  
  <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
  <ContentTemplate>
  <div>
  <table border="0" cellpadding="0" cellspacing="0" style="width: 99%; height: 50px; position: relative; top: 0px;left:5px; z-index: 101;">
  <tr>
  <td style="height:25px; width: 563px;">
  <asp:Button ID="btClear" runat="server" Text="Clear" /><asp:DropDownList ID="drpDType"
  runat="server">
  <asp:ListItem>ImportDate</asp:ListItem>
  <asp:ListItem>ShipDate</asp:ListItem>
  </asp:DropDownList>
  <asp:TextBox ID="txtFrom" runat="server"></asp:TextBox>
  <asp:Label ID="Label1" runat="server" Text="Factory" Width="59px"></asp:Label>&nbsp;
  <asp:TextBox ID="txtFactory" runat="server"></asp:TextBox>
  <br />
  <asp:Button ID="btnMore" runat="server" Text="MoreOption" Width="136px" />
  <asp:Button ID="butQuery" runat="server" Text="Go" Width="51px" OnClick="butQuery_Click" />
  &nbsp;<asp:Button ID="btnCreate" runat="server" Text="Create Order" OnClick="btnCreate_Click" />
  <asp:Button ID="butExport" runat="server" Text="Export Excel" OnClick="butExport_Click" />
  <asp:Label ID="Label2" runat="server" Width="170px" BackColor="#FFFF80" BorderColor="Black"></asp:Label>&nbsp;
  </td>
  </tr>
  </table> 
  <dx:ASPxGridView ID="ASPxGridView1" runat="server" Width="872px" AutoGenerateColumns="False">
  <Columns>
  <dx:GridViewCommandColumn ShowSelectCheckbox="True" VisibleIndex="0" Width="30px">
  <ClearFilterButton Visible="True">
  <