Backup Failing on Windows Server 2008R2

I am getting an error trying to backup several servers with Backup Exec.  I am only getting this on servers that are Windows Clustered. 

V-79-57344-850 - AOFO: Initialization failure on: "System?State". Advanced Open File Option used: Microsoft Volume Shadow Copy Service (VSS).
Snapshot provider error (0xE0000352): The specified volume does not exist. Recreate the volume, and then try the job again.

Please help.

Thanks,

Richard