Hi RH,
Here it is...
1. You cannot manage a newer version of Backup Exec with your version (actually any version) of CASO. It won't view it at all. You'd have to upgrade...
2. I had no joy managing Backup Exec 11D when I upgraded our CASO to 12.5, meaning I had to upgrade fairly quickly across the board. So Symantec recommend upgrading your clients too.
You can read up here on how to do it:
http://seer.entsupport.symantec.com/docs/304175.htm
In order to upgrade, you need to multi-step...you can do it according to the following doc:
http://seer.entsupport.symantec.com/docs/319925.htm
Laters.