How to display extention off pdf and Excel in mozila firefox

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C#

ASP.NET

PDF

hi,
i want to export my gridview in pdf and Excel but the extension doesn't display thi's my code

private void ExportGridToExcel()
{
Response.Clear();
Response.Buffer = true;
Response.ClearContent();
Response.ClearHeaders();
Response.Charset = "";
string FileName = "WebQ-Tel-Data" + DateTime.Now + ".xls";
StringWriter strwritter = new StringWriter();
HtmlTextWriter htmltextwrtter = new HtmlTextWriter(strwritter);
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.ContentType = "application/vnd.ms-excel";
Response.AddHeader("Content-Disposition", "attachment;filename=" + FileName);
GridView1.GridLines = GridLines.Both;
GridView1.HeaderStyle.Font.Bold = true;
GridView1.RenderControl(htmltextwrtter);
Response.Write(strwritter.ToString());
Response.End();

}

private void ExportGridToPDF()
{

Response.ContentType = "application/pdf";
Response.AddHeader("content-disposition", "attachment;filename=WebQ-Tel-Data" + DateTime.Now + ".pdf");
Response.Cache.SetCacheability(HttpCacheability.NoCache);
StringWriter sw = new StringWriter();
HtmlTextWriter hw = new HtmlTextWriter(sw);
GridView1.HeaderRow.Cells[0].Text = "Date et heure";
GridView1.HeaderRow.Cells[0].ForeColor = Color.Black;
GridView1.RenderControl(hw);
StringReader sr = new StringReader(sw.ToString());
Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);
HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
pdfDoc.Open();
htmlparser.Parse(sr);
pdfDoc.Close();
Response.Write(pdfDoc);
Response.End();
GridView1.AllowPaging = true;
GridView1.DataBind();
}


but in google chrome it works
plzz i need help