Dynamic Sumif

Hi,

Need your help on the sumif function..

I am trying pick up some values (Marked in grey color) in attached sheet using the Sumif function. Problem I am facing is that it is picking data of a particular month only (Jul-10) in the attached sheet...

Function that I am using is:

=IF(B6="","",SUMIF('1'!$A:$A,Review!$A6,'1'!$I:$I))

I want to make this month ('1'!$I:$I) dynamic, so that whenever a user select month of its choice in the drop down (I2), data for that month gets published...

Kindly help...

Thanks in advance..