I am generating a Crystal report in an asp.net application and keep getting the following error message when I try to export the report to pdf format.

CrystalDecisions.CrystalReports.Engine.LogOnException: Logon failed

I have crawled everywhere on the web and have found a lot written about this problem but all info relates to binding your report to sql server. In my case I am binding to an xml file.

It is driving me insane !!!
If I just display the crystal report in a viewer on a webpage it works fine. Its only when I try to export it that I have the problem.
Heres my code :

Code:
Dim crReportDocument As ReportDocument
        Dim crExportOptions As exportoptions
        Dim crDiskFileDestinationOptions As diskfiledestinationoptions
        Dim Fname As String
        crReportDocument = New ReportDocument
        crReportDocument.Load("C:\inetpub\wwwroot\TTPresentation\reports\timesheetReport1.rpt")
        Fname = "C:\inetpub\wwwroot\TTPresentation\reports\" & "test" & ".pdf"
        crDiskFileDestinationOptions = New DiskFileDestinationOptions
        crDiskFileDestinationOptions.DiskFileName = Fname
        crExportOptions = crReportDocument.ExportOptions
        With crExportOptions
            .DestinationOptions = crDiskFileDestinationOptions
            .ExportDestinationType = ExportDestinationType.DiskFile
            .ExportFormatType = ExportFormatType.PortableDocFormat
        End With
        crReportDocument.Export()
        Response.ClearContent()
        Response.ClearHeaders()
        Response.ContentType = "application/pdf"
        Response.WriteFile(Fname)
        Response.Flush()
        Response.Close()
        System.IO.File.Delete(Fname)

I beg of you. Help me or put me out of my misery.