An administrator has several expired backup sets that are still showing under the configured Disk...

There are other unexpired backup sets that are dependent on them.

The expired backup sets need to be duplicated before they will be deleted.

The expired backup sets are part of a (Simplified Disaster Recovery) SDR-enabled backup.

The expired backup sets have to be overwritten by a new backup job.

The expired backup sets need to be manually deleted from the Backup Exec console.