gridview导出到excel

Question

我写了gridview导出到excel的代码，但是点击按钮事件没有任何反应，不知道是怎么回事？

我的代码如下:

            Response.ClearContent();
            Response.Charset = "GB2312";
            Response.ContentEncoding = System.Text.Encoding.UTF7;

           
            Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncoding("通讯录.xls", System.Text.Encoding.UTF8).ToString());
            Response.ContentType = "application/excel";
            this.EnableViewState = false;
     
            StringWriter sw = new StringWriter();
            HtmlTextWriter htw = new HtmlTextWriter(sw);
            BindGridView();
            GridViewContact.AllowPaging = false;
            GridViewContact.RenderControl(htw);
            Response.Write(sw.ToString());
            Response.Flush();
            Response.End();
            GridViewContact.AllowPaging = true;