I would like to create a SUMIF expression that works across different
worksheets.

For example for one worksheet I have:

=SUM(IF(B2=AirHandlers!$A$3:$A$503,AirHandlers!$D$ 3:$D$503,0))

It works, but it only covers one worksheet. I have about 20 other
worksheets, and I'm sure there's a way of doing it without typing an IF
statement for each worksheet. What's that way?
--
Brian

PS: I tried
=SUM(IF(B2='AirHandlers:StmTraps'!$A$3:$A$503,'Air Handlers:StmTraps'!$D$3:$D$503,0)) and it did not work.