Exchange 2010 : Incremental backups, seen as Full ones

Hi,

When I use the powershell command (or the GUI) to check when did my last incremental backups occured, exchange seems to think that my incremental backups are full backups.

I use Symantec Backup Exec 2012 as backup software.

We have a DAG 2010 and 2 datastores are backed up, only the active copies.

Could someone tell me why Exchange sees these as Full backups please ?

Thanks in advance :)

Anthony.