Accumulated amount up until a chosen month - Syntax set expression

[#1]

Hi i have the following expression to show accumulated amount for the current year.

if i select a month it shows me the total irrespective which is good, pure accumlutation.

Sum ( {1 <FYear = {"$(=Dual(Max(fYear) &'/'& Max(fYear), Max(fYear)))"}> } Amount/$(Thousand))

what i would like to do now is have a comparison with last year (2012/2013) up until a certain period which would be the month i select from the month field.

Selection

Year 2013/2014

Month Jun

Any help would be greatly appreciated.

Best,

Brad