The backup of ISPconfig runs at 14:00H and 22:00H, in the notification e-mail backups which are not scheduled to run are mentioned as: No Backup scheduled.
I've found a little "bug" in the backupscript, the backup of ISPconfig is called twice in the script, when it runs e.g. at 14:00 hours the second part which is scheduled at 22:00 will give the message: No Backup scheduled. (and at 22:00 it will give the same message)
Working on it.