Backup scheduled at logoff / shutdown not working

Ok, so I followed all steps described in the users guide to make SSR 2013 perform a full system backup at log off, you know, an event-triggered backup, choosing to star the backup when "Any user logs offto the computer". However, backups are not working. I asume logging off should be equivalent to shutting down the computer (which is what I really want it to do, make a full system backup every time I shut down the computer when leaving work). I asumed that windows logs off first when you shut down the computer, but for whatever reason it doesn´t work.

Besides, in the list of event-triggered backups there is no "backup at shutdown"

Is there a way to make SSR 2013 backup at shutdown?.