Change chart expression based on selection

[Hoowling]

Hi community! 

I would like alter the chart expression based on the list box selection made. 
The expression I would like to be dynamic is: 

=Avg({<[Info Bransch]=P({$} [Info Bransch])>}[EBIT-marg Senaste])

Where [EBIT-marg Senaste] should change given my selection in the list box (EBIT-marg Senaste is a dimension). 

THankful for any help!

[chrismarlow]

Hi,

Should be;

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

Cheers,

Chris.

[Hoowling]

Hi, 

Something is not working properly with that expression:
(ps. changed  field name from bolagsnamn to bolag). 

[chrismarlow]

Hi,

I don't understand how that variable works. If you put it in a text box does it show the value you want?

Cheers,

Chris.