What is wrong with my formula?

=SUMPRODUCT((I13:I42<{"OFF","VAC",""})*(D13:D42< {"FILL",""})*C13:C42)

In Cells C13:42 I have 1's where I want them, yet this keeps coming back
with #N/A, if I remove the last "" after "FILL" it comes up with a total of
46 when it should only come up with 12!!!

Any help would be great...

Thanks,