Thank you Thomas,
Help on this is greatly appreciated.
It is working fine in my local test.
But still I am getting error. Please see attachment.
Below is my code line where I am getting this error.
Code:
  PdfDocument document = new PdfDocument();
            document.Info.Title = "A sample invoice";
            document.Info.Subject = "Demonstrates how to create an invoice.";
            document.Info.Author = "Stefan Lange";          
            // Create an empty page
            PdfPage page = document.AddPage();
          [color=#408040]  // Get an XGraphics object for drawing
            XGraphics gfx = XGraphics.FromPdfPage(page); //This line has an error
[/color]
            //XPdfFontOptions options = new XPdfFontOptions(PdfFontEncoding.Unicode, PdfFontEmbedding.Always);
            // Create a font
            XFont font = new XFont("Times New Roman", 14, XFontStyle.BoldItalic);
            gfx.DrawString(footer, new XFont("Times New Roman", 8, XFontStyle.BoldItalic), XBrushes.Black, x, y, XStringFormats.TopLeft);
            MemoryStream stream = new MemoryStream();
            document.Save(stream, false);
            Response.Clear();
            Response.ContentType = "application/pdf";
            Response.AddHeader("content-length", stream.Length.ToString());
            Response.BinaryWrite(stream.ToArray());
            Response.Flush();
            stream.Close();
            Response.End();