django 'widget_tweaks' is not a registered tag library

Witam, używam apki widget_tweaks w Django. Lokalnie działa, a na serwerze dostaję:

TemplateSyntaxError at /kontakt/

'widget_tweaks' is not a registered tag library. Must be one of:
admin_list
admin_modify
admin_static
admin_urls
cache
i18n
l10n
log
static
staticfiles
tz

Instalowałem to komendą:

pip install django-widget-tweaks

W settings.py mam:

INSTALLED_APPS = [
    ...
    'widget_tweaks',
]

A w HTML na początku jest:

{% load widget_tweaks %}

Próbowałem w shellu dostać się to widget_tweaks:

from django.apps import apps

apps.get_app_config('widget_tweaks').verbose_name

I dostałem:

Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/local/lib/python2.7/dist-packages/Django-1.10a1-py2.7.egg/django/apps/registry.py", line 155, in get_app_config raise LookupError(message) LookupError: No installed app with label 'widget_tweaks'.