How to Display Mailfilesize <computed value> in Switcher Forms for calendar for user

I created a computed value with this formule to have the mailfilesize display for the user, but it don’t work. What missing ?

When I open the database , it display only “used : mo” , and there are no mailfileSize

Quota := @Environment(“MailQuota”);

@If(Quota = “”;"Used: “+ @Environment(“MailFileSize”) + " Mo”;

"Utilisé: "+ @Environment(“MailPercent”) + “% (” + @Environment(“MailFileSize”) + "Mo sur " + Quota + “Mo)”)