Scheduled backup doesn't work - No backup in hub nor wp admin ???

Hello, it's been month that I use Snapshot and I've had a problem with my website, I never realized it wasn't working properly.
Hopefully I had made a test on dropbox but I can't make it manually, I need the auto backup.

I'm using a multisite at this adress: http://www.uplinkteam.be and see the linked screenshot show no backup, even if in the wp admin it says that next backup is ready for next monday (it allways say that and I've never had an automatic backup done).

Thank you.