Hello,
I'm getting a #ref error with the following formula. I haven't had a
problem with this until today.

=SUMPRODUCT(('ALL FF TLING'!$D$2:$D$1200=A$9)*('ALL FF
TLING'!$C$2:$C$1200=A10))

The range $D$2:$D$1200 is good and hasn't changed, as well as the
$C$2:$C$1200.

the reference to A$9 is how I want the formula to calculate for ease of
copying the formula to other cells, as well as the A10.

Like I said earlier, I had no problem with this formula in the previous
months, but when I made the monthly updates today, the error has popped
up. In the process of the updating, I do delete everything that is in
the 'ALL FF TLING' tab where the values in columns D and C are looked
at, but I have pasted data back into those cells.

Can anyone tell me why I'm getting this error?

Thanks.