error delete host

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/djextdirect/provider.py", line 256, in process_normal_request
    result = func( request, *data )
  File "/usr/share/openattic/rpcd/extdirect.py", line 116, in wrapper
    return getattr(hh, func.__name__)(*args, **kwargs)
  File "/usr/share/openattic/rpcd/handlers.py", line 313, in remove
    return self._get_model_manager().get(id=id).delete()
  File "/usr/lib/python2.7/dist-packages/django/db/models/base.py", line 695, in delete
    collector.delete()
  File "/usr/lib/python2.7/dist-packages/django/db/models/deletion.py", line 255, in delete
    sender=model, instance=obj, using=self.using
  File "/usr/lib/python2.7/dist-packages/django/dispatch/dispatcher.py", line 185, in send
    response = receiver(signal=self, sender=sender, **named)
  File "/usr/share/openattic/lio/models.py", line 349, in __acl_pre_delete
    get_dbus_object("/lio").acl_delete(instance.id)
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 70, in __call__
    return self._proxy_method(*args, **keywords)
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 651, in call_blocking
    message, timeout)
DBusException: org.freedesktop.DBus.Python.SystemError: Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/dbus/service.py", line 707, in _message_cb
    retval = candidate_method(self, *args, **keywords)
  File "/usr/share/openattic/systemd/helpers.py", line 75, in loggedfunc
    return func(*args, **kwargs)
  File "/usr/share/openattic/lio/systemapi.py", line 146, in acl_delete
    models.ACL.objects.get(id=dbus_to_python(id)).lio_object.delete()
  File "/usr/share/openattic/lio/models.py", line 330, in lio_object
    lio_tpg = self.tpg.lio_object