Exception Value: 'NoneType' object has no attribute 'latitude'

Traceback:
File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py" in get_response
  99. response = callback(request, *callback_args, **callback_kwargs)
File "/home/vagrant/ltp/loco_directory/teams/views.py" in team_ical
  94. return as_ical(get_events_and_meetings(team_object), team_object.name)
File "/home/vagrant/ltp/loco_directory/teams/views.py" in as_ical
  59. o.as_ical(calendar)
File "/home/vagrant/ltp/loco_directory/events/models.py" in as_ical
  118. event.add('geo').value = "%s;%s" % (self.venue.latitude, self.venue.longitude)