SUMPRODUCT Error

I have used SUMPRODUCT many times for many things. In a current analysis I am doing, I use it to find assumptions from a tab that has many. The problem I am having is that when I move the range, it is giving me #N/A errors. Here is an example:

This formula has no errors:
=SUMPRODUCT((Assumptions!$A$73:$A$79=$A18)*(Assumptions!$B$73:$B$79=$B18)*(Assumptions!$I$10:$CK$10=D$6)*Assumptions!$I$73:$CK$79)

However, this formula does, even though it is going just one row further down (from 79 to 80):
=SUMPRODUCT((Assumptions!$A$73:$A$80=$A19)*(Assumptions!$B$73:$B$80=$B19)*(Assumptions!$I$10:$CK$10=D$6)*Assumptions!$I$73:$CK$80)

Does anyone know why this might be happening?

That was it, Bernie. Thanks for letting me know that. I didn't know that you couldn't have #N/A's in order for this to work. There was a rogue formula, and this solved it. Thanks!