Forecasting

[Ayoub]

Hello Community

i'm working on an application abt prediction ,  and i  wrote this expression : 

if(not (sum(Réserve)),
linest_m(total
aggr(if((sum(Réserve)),(sum(Réserve))),Mois_Sin),Mois_Sin)*Mois_Sin
+linest_b(total aggr(if((sum(Réserve) ),(sum(Réserve))),Mois_Sin),Mois_Sin))

it gives me the prediction for the rest of the year by month .
My question is how can i  add another dimension , because when i select fields from the dimension called usage, i don't get the prediction that  i want  

[sunny_talwar]

What were you hoping to see what did you get? It is not very clear from this statement -> 'I don't get the prediction that I want". A little more details will help.