2.5.1 Automated Backup help

Hi all, we've just setup a new moodle production site running 2.5.1, ready for new academic year- ive populated it and just testing backup solutions- wanting to use automated course backups to a directory outside of public folder e.g. where moodledata folder is located. however my backups don't seem to be working- even when I switch destination back to course defaults- it skips them all- can anyone advice? 

thanks in advance.

Chris Chapman