datagrid导出到Excel中的问题

当用下面的代码时当生成的csv文件未保存时，sheet名有错。即sheet名的前面会加上".csv"和设的sheet名一起显示在sheet名的位置上。如当文件名是20050901.csv时，打开的Ecxel文件的标题为：20050901[0].csv,而sheet名为.csv]20050901.并且sheet不能更改，请教高手如何解决。 Response.Clear(); 
   Response.Buffer= false; 
   Response.Charset="GB2312"; 
   Response.AppendHeader("Content-Disposition","attachment;filename=test.xls"); 
   Response.ContentEncoding=System.Text.Encoding.GetEncoding("GB2312");    Response.ContentType = "application/ms-excel";    this.EnableViewState = false; 
   System.IO.StringWriter oStringWriter = new System.IO.StringWriter(); 
   System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter); 
   this.DataGrid1.RenderControl(oHtmlTextWriter); 
   Response.Write(oStringWriter.ToString()); 
   Response.End();