我的listView源码大略如下:(省掉了一些重复项)

<form runat="server" id="form1" >
 <asp:ListView ID="ListView1" runat="server">
  <LayoutTemplate>
  <table width="2000px">
  <thead>
  <tr>
  <th>ID</th>
  <th>业务类型</th>
  <th>订单编号</th>
  <th>输入</th>   
  </tr>
  </thead>
  <tbody>
  <asp:PlaceHolder runat="server" ID="itemPlaceholder" />
  </tbody>
  </table>
  </LayoutTemplate>
  <ItemTemplate>
  <tr>
  <td><%# Eval("ID") %></td>
  <td><%# Eval("ba01") %></td>
  <td><%# Eval("ba02") %></td>   
  <td>
  <asp:Button ID="btnAdd" runat="server" CommandArgument='<%# Eval("ID") %>' OnCommand="btnAdd_Command" Text="输入" />
  </td>   
  <td>
  <asp:Button ID="btndeleting" runat="server" CommandArgument='<%# Eval("ID") %>' OnCommand="btndeleting_Command" onclientclick="return confirm('是/否')" Text="删除" />
  </td>   
  <td>
  <asp:Button ID="btnediting" runat="server" CommandArgument='<%# Eval("ID") %>' OnCommand="btnediting_Command" Text="修改" />
  </td>   
  </tr>
  </ItemTemplate>
  </asp:ListView>   
</form>   

导出EXCEL的代码如下:

 protected void AC_Click(object sender, EventArgs e)
  {
  Export("application/ms-excel", "employee.xls");
  }
  private void Export(string FileType, string FileName)
  {

  Response.Charset = "GB2312";

  Response.ContentEncoding = System.Text.Encoding.UTF7;

  Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(FileName, Encoding.UTF8).ToString());

  Response.ContentType = FileType;

  this.EnableViewState = false;

  StringWriter tw = new StringWriter();

  HtmlTextWriter hw = new HtmlTextWriter(tw);

  ListView1.RenderControl(hw);

  Response.Write(tw.ToString());

  Response.End();

  }



报错的地方在 ListView1.RenderControl(hw); 报错的提示如下:
类型“Button”的控件“ListView1_ctrl0_btnAdd”必须放在具有 runat=server 的窗体标记内
我感觉这个提示有误,整个listView1控件都在form1 之内, 不知道在那里纠正,请大师指点,万分感谢.