Linear Trend Line not Visible on Reference Line

[Keitaru]

Hi,

Trying to draw a Linear Trend Line through my chart

I'm able to add it as a normal measure but not as a Reference line

=LINEST_M(Total Aggr(Count({<[Apps by Res Cat]>}[Incident ID*+]),Week),Week)*Week+
LINEST_B(Total Aggr(Count({<[Apps by Res Cat]>}[Incident ID*+]),Week),Week)