Guest Account on Managed 10.7 Client Not Working

I've got this Lion MacBook managed by a 10.6 Server to have the guest account enabled. Despite this, I am unable to log in as guest. The only thing that seems to be happening is that the checkbox to enable/disable the Guest account is greyed out. To enable the guest account, I have to disable the managed prefs to un-grey the tick box and re-able the guest account which at that point, creates the keychain for the guest account. Has anyone encountered this? I've tried baking in the enabled guest account into my OS image but that doesn't work either. I would like to find a script to enable the guest account automatically as this would be a pain to do manually.