Hi, this sounds like it is running as it should. see the description from 1048 of the Backup Exec 2012 admin guide
'About the synthetic backup feature
The synthetic backup feature eliminates the need to perform recurring full backups for supported remote resources. The synthetic backup is assembled from a full backup (called a baseline) and subsequent incremental backups.
The resulting synthetic backup then becomes the new baseline. Only incremental backups are required until the next synthetic backup is created. The synthetic backup is as current as the last incremental backup that it contains.
The components of a synthetic backup are as follows:
■ Baseline backup. The baseline backup is the first full backup to run that is associated with the synthetic backup. The full baseline backup runs one time only, and backs up all of the files on the selected computer when it runs.
■ Recurring incremental backups.Incremental backup jobs back up the files that change after the baseline backup.
■ Recurring synthetic backups. Symantec Backup Exec Advanced Disk-based Backup Option
The synthetic backup process combines the data from the baseline backup and the incremental backups to form a synthesized full backup of the selected computer. This synthesized full backup becomes a new baseline backup, whichis combined with subsequent incremental backup sets to form a new synthesized full backup.'
This is the same as explained on Page 879 of the Backup Exec 2010 Admin Guide
