Calculating age from birthdate

[yuccakid]

I have a form based on a query. Two fields are DOB and Age. The Age field datatype in the underlying table is number. I use the following as the Control Source in the Age field:
=IIf(IsNull([DOB]),"",Year(Now())-(Year([DOB])-(DateSerial(Year(Now()),Month([DOB]),Day([DOB]))>Now())))
I cannot compile because of a "syntax" error.
Help!!!