I Am Using This Code For Watermark Image For Pdf I Got Only One Page Did Not Get Every Page?

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C#

ASP.NET

PDF

watermark

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i am trying to convert aspx page to pdf with water mark image but did not get water mark for all pages i get only one page any one can resolve it? 

pdfDoc.Open();
htmlparser.Parse(sr);
iTextSharp.text.Image tsipasswm = iTextSharp.text.Image.GetInstance(Server.MapPath(filepath));
tsipasswm.Alignment = iTextSharp.text.Image.ALIGN_MIDDLE;
tsipasswm.ScaleToFit(200, 200);
tsipasswm.Alignment = iTextSharp.text.Image.UNDERLYING;
tsipasswm.SetAbsolutePosition(250, 300);
pdfDoc.Add(tsipasswm);
htmlparser.Parse(sr);
pdfDoc.Close();