What little thing am I missing? "Bummer! Hmm, didn't get the right success message from `ArticleCreate'

from django.contrib.auth.mixins import LoginRequiredMixin
from django.core.urlresolvers import reverse_lazy
from django.views import generic

from . import mixins
from . import models


class ArticleList(generic.ListView):
    model = models.Article


class ArticleDetail(generic.DeleteView, generic.DetailView):
    model = models.Article
    template_name = 'articles/article_detail.html'


class ArticleCreate(LoginRequiredMixin, mixins.SuccessMessageMixin, generic.CreateView):
    fields = ('title', 'body', 'author', 'published')
    model = models.Article
    success_message = "Article created!"


class ArticleUpdate(LoginRequiredMixin, mixins.SuccessMessageMixin, generic.UpdateView):
    fields = ('title', 'body', 'author', 'published')
    model = models.Article

    def get_success_message(self):
        obj = self.get_object()
        return "{} updated!".format(obj.title)


class ArticleDelete(LoginRequiredMixin, generic.DeleteView):
    model = models.Article
    success_url = reverse_lazy('articles:list')


class ArticleSearch(generic.ListView):
    model = models.Article

    def get_queryset(self):
        qs = super().get_queryset()
        term = self.kwargs.get('term')
        if term:
            return qs.filter(body__icontains=term)
        return qs.none()

from django.contrib import messages

class SuccessMessageMixin:
    success_message = ""

    def get_success_message(self):
        return self.success_message

    def form_valid(self, form):
        message.success(self.request, get_success_message)
        return super().form_valid(form)