Error on query using function

[bhaswar]

Hi
I wanted to calculate the number os working days in a query. So I went about wrint a function which accepts the start date end date and the calculates the number os working days:
Public Function getWorkingDays(startDate As String, endDate As String)

On Error GoTo Err_getWorkingDays

Dim intCounter As Long
Dim stDt As Date
Dim testDt As Date
Dim blnHoliday As Boolean
If IsNull(startDate) Or IsNull(endDate) Then
getWorkingDays = 0
Exit Function
End If
Debug.Print Month(startDate)
Debug.Print Month(endDate)

testDt = Format(startDate, "dd/mm/yyyy&quot
endDate = Format(endDate, "dd/mm/yyyy&quot
intCounter = 0

Do While testDt <= endDate
blnHoliday = True

Select Case testDt
Case #12/25/2003#, #12/26/2003#, #12/30/2003#, #12/31/2003#, #1/1/2004#
blnHoliday = True
Case Else
blnHoliday = False
End Select
If Weekday(testDt) = 6 Or Weekday(testDt) = 7 Then
blnHoliday = True
End If

If Not blnHoliday Then
intCounter = intCounter + 1
End If
testDt = testDt + 1
'Debug.Print testDt
Loop

getWorkingDays = intCounter

Exit_getWorkingDays:
Exit Function

Err_getWorkingDays:
Debug.Print Err.Number & Err.Description
If Err.Number = 13 Then
MsgBox (&quot;error here&quot
End If

Resume Exit_getWorkingDays

End Function

This works fine when there is a start and an end date. But whenever there is a blank end date it fails with a error 13 (type mismatch). There are also other errors that occur like 7 4 and 3.
I dont know what these other erro means!! I know 7 is out is memory, but why is it occuring?!
The query looks like:
SELECT Repairs.Customer, Repairs.[Product P/N], Repairs.[Product S/N], Repairs.[Rep Start Date], Repairs.[Rep Compl Date], Repairs.[Shipped Date], Repairs.[Stat Conf], Repairs.[Service Ref], getWorkingDays(Format([Rep Start Date],&quot;mm/dd/yy&quot,Format([Rep Compl Date],&quot;mm/dd/yyyy&quot) AS TAT
FROM (Repairs INNER JOIN [Service Types] ON Repairs.FType = [Service Types].FType) INNER JOIN Products ON Repairs.[Product P/N] = Products.SPart;

being a newbie user I am lost. Could someone point me in the right direction.
1)How to deal with the errors especially 13
2) can I put a filter on my query to prevent blank end dates to go there?

Thanks

Bhaswar

 

[MinusM]

Append at the end of the SQL ( before ; )

WHERE ([Rep Compl Date] is not null)

Best of luck