Set analysis question

[#1]

I have created a profit / loss statement. I am trying to compare same period last year.

To make this work, I use this expression:

Sum({1<Year={'=$(vLastYear)'},Period={'=$(vPeriod)'}>}Value)

vLastYear and vPeriod gets the value based on selection made by the user. If user sets year = 2014 the value is 2013. To accomplish this I use the expression =(GetFieldSelections(Year)-1). The listbox is set to only one  possible value selected.

The problem that I am having is that regardless what year I select, it is showing the result for the selected year, not the previous year.

If I change the variable $(vLastYear) with the actual year (f.example 2013), the result is correct.

I have also tried to change the {1< in the set expression to {$<, but this seems not the change anything.

I have checked the value for vLastYear, and it is giving me the correct result (in other words if I choose 2014, the value is 2013).

Hope someone can help me in the right direction.

[#2]

Found the answer myself

This worked:

Sum({$<Year={$(#vLastYear)}>}Value)

Hope someone also can use this sollution.