e000959a - An attempt to take a snapshot of a virtual machine failed because it was unable to quiesce an application

When doing backups of VM servers I get the following error and some of my backups don't comlete.

e000959a - An attempt to take a snapshot of a virtual machine failed because it was unable to quiesce an application

This happens with both Full backups and Differentials.  I am running Backup Exec 2012 fully patched.  The VMWare environment is version 5.

Any thoughts or ideas are appreciated.