Aufruf einer UDF, Fehler Objekt erforderlich

Function New_SumProduct(x As String, y As String) As Variant
Dim strMonat As String
Dim strArt As String
Dim strSumme As String
Application.Volatile
intLastRow = Sheets("Tabelle1").Range("F65536").End(xlUp).Row
strMonat = Application.Caller.Parent.Range("Tabelle1!A5:A" & intLastRow).Address ' contains  _
_
text
strArt = Application.Caller.Parent.Range("Tabelle1!C5:C" & intLastRow).Address ' contains   _
_
text
strSumme = Application.Caller.Parent.Range("Tabelle1!F5:F" & intLastRow).Address  '  _
contains values
New_SumProduct = _
Evaluate("SUMPRODUCT((" & strMonat & "=" & Chr(34) & x & Chr(34) & ")*(" & strArt & "=" &   _
_
Chr(34) & y & Chr(34) & ")*" & strSumme & ")")
End Function