Filter and array formula

[gnoorod]

Hi,

I have a very hard time to find the solution of my problem. If you are able to help, feel free to jump in!

So, I want to count the unique partner ID based on 2 criterias:

1. Years (2009, 2010 and 2011)
2. SP or SA

and each row in my table is a transaction with those partners.

So, to achive this, I use an array formula and I think the formula is ok. But, i found a glitch... If I choose:
Years: 2011
Type: SP

The result is not ok, but if I use the filter to change the order of the "year" column, the result will be ok...

Why the filter change the result of the formula and how I can avoid this?

Please use my document in the attachement for testing purpose.

Thanks for your help

Bye