SumIf with more than one condition

Hi, I'm trying create a Sum(If formula with 2 conditions, but whatever I try doesn't seem to want to cooperate. I want to add up the sum of all invoices according to the country they deal with and the month that they were created in. I've attached a sample file showing what I'm trying to accomplish.
Here is how far I've gotten so far:
=SUM(IF(Main!$L:$L;B21*Main!$Z:$Z;C20);Main!$H:$H)

I've tried other forms as well but even though this only returns #Value!, at least the formula is accepted.

Any help would be greatly appreciated!