Which version of NBU? There are known problems with certain versions where backups are being skipped without reporting any failures.
The next is to verify if backups are really being skipped - a lot of times our interpretation of what should be running when is not the same as NetBackup's point of view. There are documented scenarios with Frequency and Calendar based scheduling where NetBackup will not run certain schedules:
With calendar based schedules, daily backups should not span midnight - before and after midnight are seen as 2 separate windows, which might result in 2 backups on the same night (before and after midnight) and the backup being skipped the next evening.
With frequency based schedules, the question is: 'has enough time elapsed since the last backup?'.
In these cases, backups are being skipped because they are actually supposed to be skipped, meaning that no error will be logged and will not appear in any report of any kind.
To see if your interpretation of what should be running is the same as NetBackup's, use 'nbpemreq -predict_all -date <mm/dd/yyyy HH:MM:SS>' on a regular basis.
