VMware back-ups failing with Physical RDM's

Hi,

We have Back-up Exec 2012 SP2 installed on a Windows 2008 R2 Std. Server.
We use this setup to back-up our VMware enviroment but several VM's have Physical Disks. We have excluded these disks in the selection list, however we still keep getting a failure message on the job. How is this possible?

kind regards