Illlegal character set ERROR in BindHTML() method

hi,

I am usring following code.

Try

Dim oStringWriter As New System.IO.StringWriter()

Dim oHtmlTextWriter As New System.Web.UI.HtmlTextWriter(oStringWriter)

dtLstCompanyContacts.RenderControl(oHtmlTextWriter)

pdf.BindHTML(oStringWriter.ToString())

pdf.Save("TestFile.pdf", Aspose.Pdf.SaveType.OpenInAcrobat, Response)

Catch ex As Exception

End Try

IT GIVES ME ERROR : ILLLEGAL CHARACTER SET

can anybody help me ?