mac - Excel: How to sum values in a column based on multiple criteria

I have a list of criteria in row 20, like this:

A20: "My Company, Inc."
B20: "Client Expenses"
C20: "Travel"

The data is below, like this:

B40: "Client Expenses"
C40: "My Company, Inc."
D40: "Travel"
I40: $100

B41: "Client Expenses"
C41: "Acme, Inc."
D41: "Travel"
I41: $200

B42: "Client Expenses"
C42: "My Company, Inc."
D42: "Food"
I42: $300

B43: "Client Expenses"
C43: "My Company, Inc."
D43: "Travel"
I43: $400

I want to sum all of column I, if the criteria in A,B,C: 20 matches the data in B,C,D: 40:43

In OpenOffice Calc, this works:

=SUMPRODUCT($C$40:$C$66=A27;$D$40:$D$66=C27;$B$40:$B$66=B27;$I$40:$I$66)

In Excel for Mac OS X, it gives me $0. Can someone help me either fix this, or comes up with a different method to do the same thing?

Answer

Wrap each argument in parenthesis and add two dashes preceding them. Here it is rewritten:

=SUMPRODUCT(--($C$40:$C$66=A27),--($D$40:$D$66=C27),--($B$40:$B$66=B27),$I$40:$I$66)

That should work.