Page.register_extensions('titles', 'seo', 'symlinks', 'translations')

$ python manage.py validate 
Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 443, in execute_from_command_line
    utility.execute()
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 382, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/core/management/base.py", line 196, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/core/management/base.py", line 232, in execute
    output = self.handle(*args, **options)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/core/management/base.py", line 371, in handle
    return self.handle_noargs(**options)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/core/management/commands/validate.py", line 9, in handle_noargs
    self.validate(display_num_errors=True)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/core/management/base.py", line 266, in validate
    num_errors = get_validation_errors(s, app)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/core/management/validation.py", line 30, in get_validation_errors
    for (app_name, error) in get_app_errors().items():
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/db/models/loading.py", line 158, in get_app_errors
    self._populate()
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/db/models/loading.py", line 64, in _populate
    self.load_app(app_name, True)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/db/models/loading.py", line 88, in load_app
    models = import_module('.models', app_name)
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/home/alen/projects/django-fgps/src/app/models.py", line 12, in <module>
    Page.register_extensions('titles', 'seo', 'symlinks', 'translations')
  File "/home/alen/.virtualenvs/django-fgps/local/lib/python2.7/site-packages/feincms/extensions.py", line 80, in register_extensions
    ext, cls.__name__))
django.core.exceptions.ImproperlyConfigured: translations is not a valid extension for Page