Kevin,

It worked fine in my test spreadsheet, but when I entered the formula in my
actual worksheet, I got #NUM!

Here is my formula in Cell E14 (worksheet 2006 Jan):

=INDEX(Data!T:T,MATCH('2006 Jan'!B14 & '2006 Jan'!D14,Data!Q:Q &
Data!S:S,0),1)

Worksheet (Data):

Q S T
547745 100 -100

Worksheet (2006 Jan):
B D E
14 547745 100 (the result of the formula should be -100)