My Crystal report use store procedure as data source. Code1 is works. Once I add code2 to export to pdf, an error occured.
How to fix it?      

//code1 works fine and displays report on screen.

        Dim crd As New ReportDocument
        crd.Load(Server.MapPath("myCrystalReport.rpt"))
        crd.SetDatabaseLogon("myID", "Password", "ServerName", "DBName")
        CrystalReportViewer1.ReportSource = crd

     //code2 do not work said that "Missing parameter values" at line bold font.

       Dim exp As New ExportOptions()
        exp.ExportFormatType = ExportFormatType.PortableDocFormat
        exp.FormatOptions = New PdfRtfWordFormatOptions()
        Dim req As New ExportRequestContext()
        req.ExportInfo = exp
        Dim st As System.IO.Stream
        st = crystalReportViewer1.FormatEngine.ExportToStream(req) //Missing parameter values
        Response.ClearHeaders()
        Response.ClearContent()
        Response.ContentType = "application/pdf"
        Dim b(st.Length - 1) As Byte
        st.Read(b, 0, CInt(Fix(st.Length)))
        Response.BinaryWrite(b)