Q:

auth.authenticate() keeps returning None

Here is my problem, I want to authenticate a custom AbstractBaseUser in.
if request.POST:
        username = request.POST['username']
        password = request.POST['password']
        user = auth.authenticate(username=username, password=password)
        print user
        if user is not None:
            ...

My user's informations are username: tom, password: tom.
When I check in the shell, I have a SimpleUser with these informations, so it exits. Now when I print user in the django console, it prints None. But, when I look at the informations Django has, it says 
{'username': u'tom', u'csrf_token': <django.utils.functional.__proxy__ object at 0x7fbb681fc650>, 'errors': ['Username/password error'], 'password': u'tom'}

So from what I see, username and password are correct. What's wrong ?
Edit : Creation of SimpleUser : 
class SimpleUser(AbstractBaseUser):
    username = models.TextField(max_length=40, unique=True)
    firstname = models.TextField(max_length=40)
    lastname = models.TextField(max_length=40)
    email = models.EmailField()
    society = models.TextField(max_length=255)

    objects = UserManager()

    USERNAME_FIELD = 'username'
    REQUIRED_FIELDS = ['password', 'society', 'email']

Edit 2 : Register view in views.py :
def registerview(request):
    firstname = ""
    lastname = ""
    username = ""
    password01 = ""
    password02 = ""
    email = ""
    society = ""
    errors = []
    hlinks = [("http://localhost:8000/", "Index"),
              ("http://localhost:8000/login", "Login"),
              ("http://localhost:8000/register", "Register"), ]
    if request.POST:
        firstname = request.POST['firstname']
        lastname = request.POST['lastname']
        username = request.POST['username']
        password01 = request.POST['password01']
        password02 = request.POST['password02']
        email = request.POST['email']
        society = request.POST['society']
        if (password01 != "" and password01 == password02 and firstname != "" and lastname != "" and username != "" and email != "" and society != ""):
            try:
                SimpleUser.objects.get(username=username)
            except SimpleUser.DoesNotExist:
                try:
                    SimpleUser.objects.get(email=email)
                except SimpleUser.DoesNotExist:
                    u = SimpleUser(firstname=firstname,
                                   lastname=lastname,
                                   username=username,
                                   password=password01,
                                   email=email,
                                   society=society)
                    u.save()
                    return HttpResponseRedirect('/login/')
            errors.append(
                "invalide user/pass")
        else:
            errors.append("fill all fields")
    c = {
        'headerlinks': hlinks,
        'footerlinks': footerlinks,
        'firstname': firstname,
        'lastname': lastname,
        'username': username,
        'email': email,
        'society': society,
        'errors': errors,
    }
    c.update(csrf(request))
    return jinja_render_to_response('registerview.jhtml', c)

Edit 3 : Add my backends.py :
from models import SimpleUser

class SimpleUserAuth(object):

    def authenticate(self, username=None, password=None):
        try:
            user = SimpleUser.objects.get(username=username)
            if user.check_password(password):
                return username
        except SimpleUser.DoesNotExist:
            return None

    def get_user(self, user_id):
        try:
            user = SimpleUser.objects.get(pk=user_id)
            if user.is_active:
                return user
            return None
        except SimpleUser.DoesNotExist:
            return None

A:

This is not working because when you are creating new user you are providing password as it is. So its stored as plain text in database, not as hashed value. And when you call authenticate function it will check against hashed value.
In your register you should either use objects.create_user  or set password with set_password(password)

