Expoert Grid into pdf format but data can't display in pdf

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C#

ASP.NET

hi,I want to export grid data in pdf format this is my following code,problem occur
as pdf open but data not display. please help me ??? to solving problem

Response.ContentType = "application/pdf";
Response.AddHeader("content-disposition", "attachment;filename=UserDetails.pdf");
Response.Cache.SetCacheability(HttpCacheability.NoCache);
StringWriter sw = new StringWriter();
HtmlTextWriter hw = new HtmlTextWriter(sw);
GrdATDataView.AllowPaging = false;
GrdATDataView.DataBind();
GrdATDataView.RenderControl(hw);
GrdATDataView.HeaderRow.Style.Add("width", "15%");
GrdATDataView.HeaderRow.Style.Add("font-size", "10px");
GrdATDataView.Style.Add("text-decoration", "none");
GrdATDataView.Style.Add("font-family", "Arial, Helvetica, sans-serif;");
GrdATDataView.Style.Add("font-size", "8px");
StringReader sr = new StringReader(sw.ToString());
Document pdfDoc = new Document(PageSize.A2, 7f, 7f, 7f, 0f);
HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
pdfDoc.Open();
htmlparser.Parse(sr);

Response.Write(pdfDoc);
pdfDoc.Close();
Response.End();