Using variable in expression

[Hoowling]

Hi community, 

I'm trying to get the following expression to work

=Avg({<[Bolag]=,[Info Bransch]=P({$} [Info Bransch])>}[$(=varLönsamhet)])

where I want to calculate the average selected KPI from a list box for companies in the same sector as the selected one (Bolag = Company, Info Bransch = Sector). The KPI selected is captured in the varLönsamhet variable but how do I properly include the variable in the expression? Right now I get an error message. 

Thank you! 

Cheers,
Philip 

[jonathandienst]

Like this:

=Avg({<[Bolag], [Info Bransch] = P({$} [Info Bransch])>} $(varLönsamhet))

Assuming the variable varLönsamhet does not include an aggregation like Sum() or Count().