Problem with VcGuestProcessManager and different vCenter Versions

Hey,
this week we encountered a strange behavior of the scripting class VcGuestProcessManager, which should run a script on virtual machine using its method startProgramInGuest.
The vCO setup is designed to manage two different vCenters (5.0 and 5.1) this does work with the most scriting classes. If you try to run this from a vCO hosted on vCenter 5.0 and try to run a program on virtual machine hosted on vCenter 5.1 it will fail.

The german error message is this one:

Der Vorgang wird für dieses Objekt nicht unterstützt. (Workflow: RunProgramOnGuest / Scriptable task (item0)#22)

In english it is something like that:

The process is not supported to this object

This is roughly translated :D

We figured out that the vCenter version, the vCO is hosted on, has to be the same version as the vCenter version , where the virtual machines is hosted.