导出EXCEL，出现GridView方面的错误

使用这一方法导出EXCEL，在TempGrid.RenderControl(oHtmlTextWriter)处出现“类型“GridView”的控件“ctl00_ctl00_MainContent_ContentPlaceHolder1_GridView2”必须放在具有 runat=server 的窗体标记内。”这一错误，试问如何解决？

环境:VS2010 VB GiidView2有20行数据


Protected Sub Button4_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button4.Click

GenerateByGridView("导出", GridView2)

End Sub

Public Shared Sub GenerateByGridView(ByVal Typename As String, ByVal TempGrid As GridView)
HttpContext.Current.Response.Clear()
'HttpContext.Current.Response.Buffer = true;
HttpContext.Current.Response.Charset = "utf-8"
Dim Filename As String = Typename + ".xls"
HttpContext.Current.Response.AppendHeader("Content-Disposition", "online;filename=" + Filename)
HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("utf-8")
HttpContext.Current.Response.ContentType = "application/ms-excel"
'this.EnableViewState = false;
Dim oStringWriter As New System.IO.StringWriter()
Dim oHtmlTextWriter As New System.Web.UI.HtmlTextWriter(oStringWriter)
TempGrid.RenderControl(oHtmlTextWriter)
HttpContext.Current.Response.Write(oStringWriter.ToString())
HttpContext.Current.Response.End()
End Sub 'GenerateByGridView