Non riesco a creare un utente

Quando creo un utente, ho questa eccezione:

Environment:


Request Method: POST
Request URL: http://127.0.0.1:8000/users/user/create

Django Version: 1.8.8
Python Version: 3.5.3
Installed Applications:
['django.contrib.sessions',
 'django.contrib.messages',
 'whitenoise.runserver_nostatic',
 'django.contrib.staticfiles',
 'octonet',
 'hostqueue.apps.HostQueue',
 'firewall.apps.Firewall',
 'dhcp.apps.Dhcp',
 'dansguardian.apps.DansGuardian',
 'host.apps.Host',
 'polygen.apps.Polygen',
 'upgrade.apps.Upgrade',
 'asterisk.apps.Asterisk',
 'samba.apps.Samba',
 'users.apps.Users',
 'script.apps.Script',
 'quota.apps.Quota',
 'printers.apps.Printers',
 'auth.apps.Auth']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'whitenoise.middleware.WhiteNoiseMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'octonet.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']


Traceback:
File "/home/mark/truelite/FUSS/octonet/django/core/handlers/base.py" in get_response
  132.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/mark/truelite/FUSS/octonet/django/views/generic/base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)
File "/home/mark/truelite/FUSS/octonet/octonet/mixins.py" in dispatch
  105.         return super().dispatch(request, *args, **kw)
File "/home/mark/truelite/FUSS/octonet/django/views/generic/base.py" in dispatch
  89.         return handler(request, *args, **kwargs)
File "/home/mark/truelite/FUSS/octonet/django/views/generic/edit.py" in post
  215.             return self.form_valid(form)
File "/home/mark/truelite/FUSS/octonet/users/views.py" in form_valid
  510.         self.user = self.root_tree.lcreate(["users", "users", name], user_data)
File "/home/mark/truelite/FUSS/octonet/octofuss/xmlrpc.py" in lcreate
  84.         return self._wrap_call(self.server.create, "/".join(path), dumps(value))
File "/home/mark/truelite/FUSS/octonet/octofuss/xmlrpc.py" in _wrap_call
  42.                 raise globals().get(name, UnknownException)(msg)

Exception Type: UnknownException at /users/user/create
Exception Value: ' is not a valid group'

E il campo di gruppo non mi permette di inserire nessun gruppo, mi dice “No results found” quando ci clicco sopra, quindi non ho modo di inserire nessun gruppo, e la creazione fallisce per questo.