Notification issue with "my friends" app

I have a problem concerning the notifications of the "my friends" app. The app works normally and I can see all my friends on the map, but I can't recieve any geolocalisation alert. I can program such alerts, but nothing happens when the friend enters or leaves the given perimeter. This seems not a to be a bad utilisation of the app, because my wife has the same phone, I checked everything and it works on her phone.

Nothing that I found here

iCloud : dépannage de l’application Localiser mes amis - Assistance Apple

works for me. The notifications are activated for this app, and I really don't understand what's going on.

Iphone 5S

iOS 8.4