I'm using Django 1.2.3 and South 0.7.3.

I am trying to convert my app (named core) to use Django-South. I have a custom model/field that I'm using, named ImageWithThumbsField. It's basically just the ol' django.db.models.ImageField with some attributes such as height, weight, etc.

While trying to ./manage.py convert_to_auth core I receieve South's freezing errors. I have no idea why, I'm Probably missing something...

I am using a simple custom Model:

from django.db.models import ImageField

class ImageWithThumbsField(ImageField):
    def __init__(self, verbose_name=None, name=None, width_field=None, height_field=None, sizes=None, **kwargs):
        self.verbose_name=verbose_name
        self.name=name
        self.width_field=width_field
        self.height_field=height_field
        self.sizes = sizes
        super(ImageField, self).__init__(**kwargs)

And this is my introspection rule, which I add to the top of my models.py:

from south.modelsinspector import add_introspection_rules
from lib.thumbs import ImageWithThumbsField

add_introspection_rules(
    [
        (
            (ImageWithThumbsField, ),
            [],
            {
                "verbose_name": ["verbose_name", {"default": None}],
                "name":         ["name",         {"default": None}],
                "width_field":  ["width_field",  {"default": None}],
                "height_field": ["height_field", {"default": None}],
                "sizes":        ["sizes",        {"default": None}],
            },
        ),
    ],
    ["^core/.fields/.ImageWithThumbsField",])

This is the errors I receieve:

! Cannot freeze field 'core.additionalmaterialphoto.photo'
! (this field has class lib.thumbs.ImageWithThumbsField)
! Cannot freeze field 'core.material.photo'
! (this field has class lib.thumbs.ImageWithThumbsField)
! Cannot freeze field 'core.material.formulaimage'
! (this field has class lib.thumbs.ImageWithThumbsField)

! South cannot introspect some fields; this is probably because they are custom
! fields. If they worked in 0.6 or below, this is because we have removed the
! models parser (it often broke things).
! To fix this, read http://south.aeracode.org/wiki/MyFieldsDontWork

Does anybody know why? What am I doing wrong?