'Custom clean method.'

def clean(self):

    super(GroupAdminForm, self).clean()
    profile = self.request.user.userprofile
    if (not profile.is_manager):
        msg = _(u'You    need    to    be    the    administrator    of    this    group    in    order    to    edit    this    section.')
        raise forms.ValidationError(msg)
    return self.cleaned_data
