Adding trend -line slope to pivot table

[MichalSa]

Hi 

I'm trying to show in a pivot table -  the slope of the trendline per agent
This is to determine if the trend of cases created is increasing or decreasing.

I'm using the below - but not getting any results:

Dimension: Agent

Measures: LINEST_M (aggr (count( distinct [Case.id]),[Agent], [Created Week])) 

Appreciate any assistance!