crystal reports (urgent)

Public crxapplication As CRAXDRT.Application
Public crxreport As CRAXDRT.Report

Dim strReportName As String
Dim Fltr
crxapplication = New CRAXDRT.Application

'Pass the reportname to string variable
strReportName = "CITIES"

'Get the Report Location
Dim strReportPath As String = "C:\ReportViwer\ReportViwer" & "\" & strReportName & ".rpt"
'Check file exists
If Not IO.File.Exists(strReportPath) Then
Throw (New Exception("Unable to locate report file:" & vbCrLf & strReportPath))
End If
crxreport = crxapplication.OpenReport(strReportPath)
crxreport.DiscardSavedData()

'Delete all the original parameter values from the parameter picklist.
'If you want to keep the orginal parameter values in the parameter picklist, comment out this loop.
Do Until crxreport.ParameterFields(1).NumberOfDefaultValues = 0
crxreport.ParameterFields(1).DeleteNthDefaultValue(1)
Loop
crxreport.Database.Tables(1).SetDataSource(RS, 3)
' Read the records to force the parameter box to appear before sending data to the viewer
crxreport.ReadRecords()
Fltr = "{CITY_CITIES.COUNTRY_NO}={?COUNTRY_NO}"
' Get the value the user enters in the parameter box then send that text to the formula field (that ' the report is grouped on)
crxreport.RecordSelectionFormula = Fltr
' View the report
AxCrystalActiveXReportViewer1.ViewReport()
End Sub

The error I am getting is An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in axinterop.crystalactivexreportviewerlib10.dll

Additional information: Unspecified error

Can I have your help please.Which line are you getting the error?