What am I doing wrong he

=SUMPRODUCT(AL3:AL84="3/1/2006")*(AP3:AP84=6)

I want to count the number of times AL3:AL84 = 3/1/2006 AND AP3:AP84 = 6.
I keep getting ZERO when this is a non zero number. I have entered it with
CTRL SHIFT ENTER (I think that's it) and it has {} around it.

Thanks,
Barb Reinhardt