I am attempting to move an Excel formula from a worksheet and place it
in an Excel VBA function.

Naively, I thought that I could simply take the worksheet equation,
pass it variables, and add "Application." to all worksheet
function. I took the "Application." out of the VBA function to make it
easier to read.

Unfortunately this does not work for the OFFSET function, but I have
not been able to figure out just why.

Excel Worksheet Function:
=SUMPRODUCT(OFFSET(CI9,-MIN(CF9-Year_First,Fac_Depr),0,MIN(CF9-Year_First+1,Fac_Depr+1),1),
OFFSET(FirstInvFacTangDrillDepr,-MIN(CF9-Year_First,Fac_Depr),0,MIN(CF9-Year_First+1,Fac_Depr+1),1))

CF9,CI9 and named cells are single cells as opposed to multiple ones
such as in a range

Attempted Excel VBA Function:
Function FirstYearDepreciation(Current_Year, Year_First, Fac_Depr,
FirstInvFacTangDrillDepr, Eligible_Depr)
Dim Current_Year As Double
Dim Year_First As Double
Dim Fac_Depr As Integer
Dim FirstInvFacTangDrillDepr As Double
Dim Eligible_Depr As Variant

FirstYearDepreciation = SumProduct( _
Offset(Eligible_Depr, -Min(Current_Year - Year_First, Fac_Depr), 0,
Min(Current_Year - Year_First + 1, Fac_Depr + 1), 1), _
Offset(FirstInvFacTangDrillDepr, -Min(Current_Year - Year_First,
Fac_Depr), 0, Min(Current_Year - Year_First + 1, Fac_Depr + 1), 1))

End Function


Can anyone shed some light on this?

Thanks in advance.

Floyd