When I assign a budle to a single user or a workstation, workstationgroup or zenworks user group, everything works fine.

Assignment to a eDirectory-group will not work. I can choose a group and save the assignment, but it will not be executed. It seems in Zenworks management center, that the icon for group objects will be shown a little bit more bright or pale as other objects.
No change if the group resides in the same or in another organisational unit as the users.

Isn't it possible to do this kind of bundle assignment for eDirectory groups?