Conditions on a box plot

[Taylorcc]

Hello, 

I have a box plot with the following data: 

Dimension = Referral Number 

Y axis = Reason for treatment 

X axis = (Referral commenced date-referral date) 

I only want the box plot to display patients aged 0-25 - where do I add age? 

I tried the following as my dimension and it didn't work -

Aggr(Only({$<[Patient Age]={">=0<=25"}>} [Referral Number]), [Referral Number])

Thank you 

[Sammy_AK]

use the set analysis parameter [Patient Age]={">=0<=25"}>} in the measure.