If when parameter is set to a time, it will silently fail
If the when parameter is set like this:
when = 01:00
backupninja's isnow() function will take that time and consider it to be the 'whendayofweek' and will never match against anything. As a result, the backups will never run, and no error is generated because every time backupninja runs, it thinks that the existing time does not match the time that backups should be run, so it decides not to run, every single time.
(from redmine: created on 2009-03-09)