Automatic course schedule not updating

Hi,

I've done a successful test of the automatic course backup feature last Friday night.  However, when attempting to setup a more complete test with backups made every night of the week, the backup schedule will not update to reflect my changes.  It was initially set to perform a backup on a Friday night only (successful).  Following changing the settings to every night, the backup report still says that the next backup will be on the next Friday night.  The _backup_courses also reflects this (as you would expect).  

Any suggestions for how to force the updated backup schedule to be respected?

Thanks.