title: Can't sign in to Django admin
body: <p>I can't sign in to Django admin with any of the superusers I've created. Tried creating new superusers, changing passwords, etc. - no error messages for any of these processes, but still can't sign in.</p>
  
  <p>I'm not sure if it's related, but I also can't run django-admin.py commands. Here is what I've done so far:</p>
  
  <pre><code>$ django-admin.py validate  
  Error: Settings cannot be imported, because environment variable DJANGO_SETTINGS_MODULE is undefined.  
  $ export DJANGO_SETTINGS_MODULE=mysite.settings  
  $ django-admin.py validate  
  Error: Could not import settings 'mysite.settings' (Is it on sys.path? Does it have syntax errors?): No module named mysite.settings
  </code></pre>
  
  <p>sys.path shows ['/Users/joerobinson/Sites/django/mysite' ... (other stuff on path)]</p>
  
  <p>Is there something else I need to do to register the mysite module?</p>
  
  <p>python manage.py runserver works fine.</p>
  
  <p><strong>Conclusion</strong><br>
  For the question about logging in to django admin, I did not have django.contrib.auth.backends.ModelBackend included in my AUTHENTICATION_BACKENDS - adding this allowed me to sign in to admin.</p>
  
  <p>I'm still working on the django-admin.py configuration question (which appears to not be related), and will reopen it in a separate question.</p>