[Zope] adding a new Tracker does not work

[Roel Van den Bergh]

I installed tracker and cmf-hack for the tracker without any problems
when i want to add a tracker I get the following error

Site Error
An error was encountered while publishing this resource.

Error Type: AttributeError
Error Value: __getitem__

Traceback (innermost last):
  File /home/zope/2-5-0/lib/python/Products/Hotfix_2002-04-15/__init__.py,
line 51, in publish_module
  File /home/zope/2-5-0/lib/python/ZPublisher/Publish.py, line 114, in
publish
  File /home/zope/2-5-0/lib/python/Zope/__init__.py, line 159, in
zpublisher_exception_hook
    (Object: Fortis)
  File /home/zope/2-5-0/lib/python/ZPublisher/Publish.py, line 98, in
publish
  File /home/zope/2-5-0/lib/python/ZPublisher/mapply.py, line 88, in mapply
    (Object: invokeFactory)
  File /home/zope/2-5-0/lib/python/ZPublisher/Publish.py, line 39, in
call_object
    (Object: invokeFactory)
  File /home/zope/2-5-0/lib/python/Products/CMFCore/PortalFolder.py, line
335, in invokeFactory
    (Object: Fortis)
  File /home/zope/2-5-0/lib/python/Products/CMFCore/TypesTool.py, line 701,
in constructContent
    (Object: portal_types)
  File /home/zope/2-5-0/lib/python/Products/CMFCore/TypesTool.py, line 483,
in constructInstance
    (Object: Tracker)
  File /home/zope/2-5-0/lib/python/OFS/Traversable.py, line 163, in
restrictedTraverse
    (Object: Tracker)
  File /home/zope/2-5-0/lib/python/OFS/Traversable.py, line 148, in
unrestrictedTraverse
    (Object: Tracker)
AttributeError: (see above)

Any suggestions?
TIA Roel

Running zope 2.5.1 with hotfixes 2002-03-01 and 2002-04-15 and cmf 1.2 on
linux redhat