The ADSM account must have these rights:

Backup files and directories
Restore files and directories
Manage auditing and security logs

I've also found that if the account belongs to more than one group, *each*
group must have these rights. If one group does not have the rights, then the
account does not have the right.

Just for a sanity check, try running the schedule service using the system
account to see if that gets a backup.

Andy Raibeck
ADSM Level 2 Support