[Zope] CoreSessionTracking install Problem

After installing CoreSessionTracking, I received this error when starting Zope: 2001-12-05T15:36:57 ERROR(200) Zope Couldn't install CoreSessionTracking Traceback (innermost last): File /home/org/lib/python/OFS/Application.py, line 668, in install_product (Object: Zope) (Info: CoreSessionTracking) File /home/org/lib/python/Products/CoreSessionTracking/__init__.py, line 97, in initialie File /home/org/lib/python/App/ProductContext.py, line 233, in registerClass File /home/org/lib/python/Interface/Util.py, line 66, in instancesOfObjectImplements (Object: SessionIdManager) File /home/org/lib/python/Interface/Util.py, line 72, in _wi (Object: SessionIdManagerInterface) TypeError: loop over non-sequence Any Ideas?