Error with django cms

Hi,

I have set up a project using django cms in my webfaction account, mostly following this tutotial : http://racingtadpole.com/blog/django-cms-with-webfaction

I have done everything except creating the database, which returns the following error :

AttributeError: 'function' object has no attribute 'decode'

And when I go to the main page of my site, here is the error I get :

Environment:

Request Method: GET
Request URL: url

Django Version: 1.5.2
Python Version: 2.7.5
Installed Applications:
('django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'djangocms_text_ckeditor',
 'cms',
 'cms.stacks',
 'mptt',
 'menus',
 'south',
 'sekizai',
 'djangocms_admin_style',
 'django.contrib.admin',
 'cms.plugins.file',
 'cms.plugins.flash',
 'cms.plugins.googlemap',
 'cms.plugins.link',
 'cms.plugins.picture',
 'cms.plugins.snippet',
 'cms.plugins.teaser',
 'cms.plugins.video',
 'reversion')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'django.middleware.doc.XViewMiddleware',
 'django.middleware.common.CommonMiddleware',
 'cms.middleware.page.CurrentPageMiddleware',
 'cms.middleware.user.CurrentUserMiddleware',
 'cms.middleware.toolbar.ToolbarMiddleware',
 'cms.middleware.language.LanguageCookieMiddleware')

Traceback:
File "/home/namor/webapps/app_django/lib/python2.7/django/core/handlers/base.py" in get_response
  92.                     response = middleware_method(request)
File "/home/namor/webapps/app_django/lib/python2.7/django/middleware/locale.py" in process_request
  21.         check_path = self.is_language_prefix_patterns_used()
File "/home/namor/webapps/app_django/lib/python2.7/django/middleware/locale.py" in is_language_prefix_patterns_used
  56.         for url_pattern in get_resolver(None).url_patterns:
File "/home/namor/webapps/app_django/lib/python2.7/django/core/urlresolvers.py" in url_patterns
  347.         patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "/home/namor/webapps/app_django/lib/python2.7/django/core/urlresolvers.py" in urlconf_module
  342.             self._urlconf_module = import_module(self.urlconf_name)
File "/home/namor/webapps/app_django/lib/python2.7/django/utils/importlib.py" in import_module
  35.     __import__(name)
File "/home/namor/webapps/app_django/app/app/urls.py" in <module>
  6. admin.autodiscover()
File "/home/namor/webapps/app_django/lib/python2.7/django/contrib/admin/__init__.py" in autodiscover
  29.             import_module('%s.admin' % app)
File "/home/namor/webapps/app_django/lib/python2.7/django/utils/importlib.py" in import_module
  35.     __import__(name)
File "/home/namor/webapps/app_django/lib/python2.7/cms/admin/__init__.py" in <module>
  9. plugin_pool.plugin_pool.discover_plugins()
File "/home/namor/webapps/app_django/lib/python2.7/cms/plugin_pool.py" in discover_plugins
  20.         load('cms_plugins')
File "/home/namor/webapps/app_django/lib/python2.7/cms/utils/django_load.py" in load
  42.         get_module(app, modname, verbose, failfast)
File "/home/namor/webapps/app_django/lib/python2.7/cms/utils/django_load.py" in get_module
  21.         module = import_module(module_name)
File "/home/namor/webapps/app_django/lib/python2.7/django/utils/importlib.py" in import_module
  35.     __import__(name)
File "/home/namor/webapps/app_django/lib/python2.7/cms/stacks/cms_plugins.py" in <module>
  7. from cms.stacks.models import StackLink, Stack
File "/home/namor/webapps/app_django/lib/python2.7/cms/stacks/models.py" in <module>
  21. class Stack(models.Model):
File "/home/namor/webapps/app_django/lib/python2.7/cms/stacks/models.py" in Stack
  34.     content = PlaceholderField(stack_slotname, verbose_name=_(u'stack content'), related_name='stacks_contents')
File "/home/namor/webapps/app_django/lib/python2.7/cms/models/fields.py" in __init__
  13.         validate_placeholder_name(slotname)
File "/home/namor/webapps/app_django/lib/python2.7/cms/utils/placeholder.py" in validate_placeholder_name
  41.         name.decode('ascii')

Exception Type: AttributeError at /
Exception Value: 'function' object has no attribute 'decode'

The static files seem to be working as I can reach them. I don't really understand the problem since the project is working locally.

Thank you for your help :)