When using a proxy model:
class Uf(models.Model): ... class CustomUf(Uf): class Meta: proxy = True class CustomUfAdmin(admin.ModelAdmin) admin
Ok, Chris remark about content types gave me the hint...
I made the mistake to define the proxy object in "admin.py". This way, you have to be superadmin to access it.
If I define the proxy object in models.py, then the content type appears and everything works fine...