I'm having a hard time with my sumif/sumproduct formulas. From the data
below, if I enter the following formula:

=SUM(IF((B2:B7="A")*(C2:C7="July"),D2:D7)) CTRL + SHFT + ENTER

I get the answer of $150 - which is what I want. However, this table gets
bigger with every transaction and every month. If, in the previous formula,
I try to include a bigger range than what actually has info in it, it returns
#VALUE. I don't want to keep changing my formula each month. What can I do
to include blank cells i.e. a range of A2:A100?

PS I tried Sumproduct as well and it produced the same results.

Product Customer Month Amount
Pizza A July $150
B July $200
C July $100
Drinks A August $300
B August $250
C August $50

Thanks
Peanut