something basic is wrong, (boy do i feel stupid)

on my worksheet i have the user defined funtcion entered like this:
TotalAmount(E11,B20)

the function in part reads like this (i've reduced it as much as possible,
so as is, it may sound a little curious, but this should isolate my
problem -i don't work) :

Public Function TotalAmount(Name)
Application.Volatile
Dim r as integer
r = 3
Dim SubTotal
SubTotal = 0
With Worksheets(Sheet2)
Do While r < 250
If .Range("B" & CStr(r)).Value =
worksheets(sheet1).range("Name").value Then
SubTotal = SubTotal + .Range("D" & CStr(r)).Value
End If
r = r + 1
Loop
End With
TotalAmount = SubTotal
End Function


thanks in advance,
mark