Backups failing - "Ready; No idle devices are available"

All of a sudden, Backup Exec 2012 is not running most of my jobs.

The job status stays at "Ready; No idle devices are available"

It ran 2 of the backups but I'm not sure why it didn't run the others.

I have 2 drives, but it would only use one at a time. Both initially have a status of 'Online.' When I was able to get one of my backup jobs running, it would load into one drive, that status would change to 'Active.' Then, if I try to run another job, the other drive will change to 'Active' for a moment, then go back to 'Online' and the job status goes to "Ready; No idle devices are available"

These are the things I've tried:

• Shutting down and restarting the server and the backup device
• Restarting the Backup Exec services
• Pausing and unpausing the backup drives

What else can I try?