Dashboard - Counts of ticket in a specific statut by aging intervals

Hi all!
I’m trying to build a new dashboard showing how many tickets are in a specific status (waiting for analysis) by LOB by Age inteval.
Unfortunatly, the age interval count since the ticket has been created and not since the ticket as been move to the “'waiting for analysis” status.

I thought by defining a new calculated member into age interval I could fix this, but I need help.
Is anyone know how to use age interval since a ticket got a specific status instead of since it’s creation?