Backup H-V-Host & Guest

Media-Server: W2k8R2 standard, fully patched, BackupExec 2012, SP1,HF180964,199866,200433,199190,201596,203574,205111

H-V-Host: W2k8R2 Enterprise, fully patched, Agent installed, full backup no GRT

H-V-Guests: 2 x W2003 (no agent installed) and 2 x W2k8R2 standard (agent for sql-backup installed)

Backup fails with V-79-57344-37953 Agent incompatible, although we installed the agent 3 times successfully. Counting the GB's we did backup the guest

and can select the vm's in the restore-job. Does BE2012 requires to install the agent on all 4 vm's?