Hello ! I created a SharePoint group in which I added myself.

In particular, I indicated this code on the “On Start” property of my Power Apps application:
ClearCollect(GRP_DEV_XXXXXXXXXXXXX; 'GroupesOffice365'.ListGroupMembers("16").value);;
Set(Var_Utilisateur_Est_XXX; !IsEmpty(Filter(GRP_DEV_XXXXXXXXXXXXX; mail = User().Email)));;
But when I specify this in the "visible" property of a button, I don't see the button.

Can you help me please ? Thanks in advance !