[Zope] inheritance in python product

[Sylvain Thénault]

hello, 

I've a problem to have a class which inherits from zope base classes
(Role.RoleManager, Acquisition.Implicit, ObjectManager.ObjectManager and
Persistent) and classes from another package.
As soon as a class inherits from one of the zope base class, I get an
exception when I try to instantiate an object of this class. This
exception is raised when I try to call the ancestor constructor:

 ZNodeImpl.__init__(self, id, title)
 TypeError: unbound method __init__() must be called with instance as
 first argument

this sounds like my class doesn't inherit from ZNodeImpl but it does !!
If I remove the zope base class, everything works correctly...

it seems to have some python black magic here. Anybody can explain this
to me or give some pointers ?

TIA

-- 
Sylvain Thénault