Pdf blank in deployment server

Hi,

I have been used ut html converter:

PdfPage page = doc.Pages.Add();
string urlToConvert = ConfigurationManager.AppSettings["ip"];

using (var converter = new HtmlConverter())
{

HtmlToPdfResult result = converter.Convert(urlToConvert + "Home/SelectedDashboardPdfView?ID=" + Session["nDashboardId"].ToString(), ImageType.Metafile,
(int) page.GetClientSize().Width, -1, AspectRatio.KeepWidth);
result.Render(page, new PdfLayoutFormat());
}

However, when i'm deployed the publish codes in our production server the pdf become blank.nothing see in the pdf files.
Please help.we need it ASAP.