I want to backup a clustered drive using backup exec 7.3. rev 2575 (second

We have backup exec installed on a seperate, dedicated backup server.

We have two physical servers and one "virtual server"

CIBG-NODE-TOR01, CIBG-NODE-TOR02 (the physical servers) and CIBG-SRV-TOR01
(our "virtual" cluster

I can back up the two physical servers with no problems, however I when
back up the clustered drive,
it will backup the data, but will fail on the OFO option, presumably because
there is no way to physically install
the acelerator agent or OFO agent on a "virtual" server.....

my questions are :

1) What is the level of compatibilty between Microsoft Cluster, and BE 7.3.
2) Is there an extra option we need to buy, or a workaround for this
problem ?

I've attached the logs from the backups of out three servers.