Correct NPV function

Hello!

I would like to create correct NPV function in excel (because the one built-in excel do not include cash-flow form period 0).Below I list my objects:

1.Count NPV
2.User selects range (rows are adjacent, each below other in one column)
3.Users inputs interest rate as a number (not percentage, in order to speed up calculation)
4.First row from selection is divided by 0, next (1+i)^ (number of row in selection); i - it is interest rate

I have written the code, but it doesn't work. Could you help me please?

Function MNPV(interest_rate As Double, flow())

Dim i As Integer

MNPV = 0


For i = 0 To UBound(flow)

flow(i) = flow(i) / ((1 + interest_rate / 100) ^ i)
MNPV = MNPV + flow(i)
Next i

End Function