[Django-users] error in AUTHENTICATION using socialregistration

hi,
    I am getting error -

       NoReverseMatch at /login/

    u'facebook' is not a registered namespace inside 'socialregistration'

when I am clicking on login link. I have installed all required things using documantation -
    http://django-socialregistration.readthedocs.org/en/latest/contrib/facebook.html
but it's showing error.
Please help me... I am unable to find this error.

settings.py- i have added-
INSTALLED_APPS = (
     'apps.socialregistration',
     'apps.socialregistration.contrib.facebook',
     )

and
AUTHENTICATION_BACKENDS = (
         'django.contrib.auth.backends.ModelBackend',
         'apps.socialregistration.contrib.facebook.auth.FacebookAuth',
)

FACEBOOK_APP_ID = '278691145597349'
FACEBOOK_SECRET_KEY = '359ed87e4cc3b3cdf2e567f7ab043d8c'

and in login.html page
i have added-
{% load facebook %}
{% facebook_button %}

thanks in advance.