SUMPRODUCT with INDIRECT

I have checked all question related to this topic, but none of it helped.

i have a formula

=SUMPRODUCT((INDIRECT("Ap"&ROW()&":"&"Ap"&(ROW()+$T4-1)));(INDIRECT("Ap"&ROW()&":"&"Ap"&(ROW()+$T4-1))))

This results in - 0.

=SUMPRODUCT((INDIRECT("Ap"&ROW()&":"&"Ap"&(ROW()+$T4-1)))*(INDIRECT("Ap"&ROW()&":"&"Ap"&(ROW()+$T4-1))))

This results in - "VALUE!

With SUM command everything worked fine, but i'm stucked with this now. I use MO 2013 and i can't seem to find out the problems with this INDIRECT function, since it works nicely with other command.

Your feedback is much appreciated!

Gasper