Problems installing django-orm-cache

[luismmontielg]

Im trying to use ormcache but I get this error:

AttributeError: 'SortedDict' object has no attribute 'append'
....
File "/home/luis/virtualenvs/..../lib/python2.6/site-packages/django/utils/importlib.py", line 35, in import_module
import(name)
File "/home/luis/virtualenvs/.../......hub/csc/models.py", line 259, in
class Category(CachedModel):
File "/home/luis/virtualenvs/...../src/django-orm-cache/ormcache/models.py", line 77, in new
new_class._meta.parents.append(base)
AttributeError: 'SortedDict' object has no attribute 'append'