Pdf to Tiff file covert in vb.net using PdfSharp.dll

i am using Pdfsharp.dll to convert tiff image to pdf file in vb.net, and it is successfull when i run in my machine, when i use it from other machine, which shows the Error like "Raw string contains invalid character with a value > 255.", please any one help me to fix error, i using the PdfSharp.dll library and the following code

    Dim objDoc As PdfDocument
    Dim objPdfPage As PdfPage
    Dim objTiffImg As Image
    Dim objXImg As XImage
    Dim iPageCount As Integer
    Dim objXgr As XGraphics
    Dim sPdfFile As String = Nothing
    Dim objDir As DirectoryInfo
    Dim objFile As FileInfo()
    Dim objFileInfo As FileInfo

    Try
        objTiffImageSpliter = New TiffImageSplitter()
        objDoc = New PdfDocument
        iPageCount = objTiffImageSpliter.GetPageCount(sFileName)

        For iCount As Integer = 0 To iPageCount - 1
            objPdfPage = New PdfPage
            objTiffImg = objTiffImageSpliter.getTiffImage(sFileName, iCount)
            objXImg = XImage.FromGdiPlusImage(objTiffImg)
            'objPdfPage开发者_高级运维.Height = objXImg.PointWidth
            'objPdfPage.Width = objXImg.PointHeight
            objDoc.Pages.Add(objPdfPage)
            objXgr = XGraphics.FromPdfPage(objDoc.Pages(iCount))
            objXgr.DrawImage(objXImg, 10, 10)
        Next
        sPdfFile = System.Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) & "\MY_FaxFile\"

        If System.IO.Directory.Exists(sPdfFile) Then
            objDir = New DirectoryInfo(sPdfFile)
            objFile = objDir.GetFiles()

            For Each objFileInfo In objFile
                objFileInfo.Delete()
            Next

            sPdfFile &= "MyFax.pdf"
        Else
            System.IO.Directory.CreateDirectory(sPdfFile)
            sPdfFile &= "MyFax.pdf"
        End If

       objDoc.Save(sPdfFile)   ' This Line shows the Error.
        objDoc.Close()
    Catch ex As Exception
        MsgBox(ex.ToString)
        sPdfFile = Nothing
    End Try

    Return sPdfFile

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I'm not familiar with this library, but based on your code and error message, I would guess that your App Data folder contains non-ASCII characters and that the PdfSharp library does not support non-ASCII characters in the filename.