Проблема с forms в django

class Comment(models.Model):
    author = models.CharField(max_length=255)
    url = models.URLField(blank=True)
    email = models.EmailField(blank=True)
    article = models.ForeignKey(Article)
    text = models.TextField()
    created = models.DateTimeField(auto_now_add=True)
    def __unicode__(self):
        return self.email

class CommentForm(forms.Form):
    author = forms.CharField(max_length=255)
    url = forms.URLField()
    email = forms.EmailField()
    text = forms.CharField(widget=forms.Textarea())
    article = forms.IntegerField(widget=forms.HiddenInput())

    <form action="/comments/add/" method="post">[u][b]{% csrf_token %}[/b][/u]
        {{ comment_form.as_p }}
        <input type="submit" value="Готово" />
    </form>

def comment_add(request):
    if request.method == 'POST':
        form = CommentForm(request.POST)
        params = {'comment':form,}
        return render_to_response("comment.html",params)