Are these backup sets dependent upon other sets ?
Verbatim from admin guide -
For example, you can specify to keep the backup sets from a full backup for two weeks. After two weeks, the backup sets expire and Backup Exec can reclaim that disk space. If you later create an incremental backup, Backup Exec keeps the full backup sets for two weeks, plus the amount of time that it keeps the incremental backup sets. If you keep the incremental backup sets for four weeks, then Backup Exec keeps the full backup sets for six weeks. The data from a full backup is kept as long as the data from its associated incremental backups. Backup Exec does not expire backup sets from a job that depends on another job until the data retention expires for all of the associated jobs...
Secondly, do these backup sets have 'Retain' enabled ? Check from the Storage tab, right-click the backup sets..and see if Retain is enabled or not..
