[Zope] ZDiscussions instalation problems

[Agata Cruickshank]

When trying to install ZUBB product (I've tried versions ZDiscussions-0.6.0
and 0.7.1 with the same result) I seem to be able to install the product
correctly, but when attempting to create an instance of ZDiscussion Topic
(after entering ID and Title) I get the following error:

Site Error
An error was encountered while publishing this resource.

NameError

Sorry, a site error occurred.

Traceback (innermost last):
  File C:\PROGRA~1\Zope1\lib\python\ZPublisher\Publish.py, line 223, in
publish_module
  File C:\PROGRA~1\Zope1\lib\python\ZPublisher\Publish.py, line 187, in
publish
  File C:\PROGRA~1\Zope1\lib\python\Zope\__init__.py, line 226, in
zpublisher_exception_hook
    (Object: ZDTopic_factory)
  File C:\PROGRA~1\Zope1\lib\python\ZPublisher\Publish.py, line 171, in
publish
  File C:\PROGRA~1\Zope1\lib\python\ZPublisher\mapply.py, line 160, in
mapply
    (Object: ZDTopic_add)
  File C:\PROGRA~1\Zope1\lib\python\ZPublisher\Publish.py, line 112, in
call_object
    (Object: ZDTopic_add)
  File C:\PROGRA~1\Zope1\lib\python\OFS\DTMLDocument.py, line 199, in
__call__
    (Object: ZDTopic_add)
  File C:\PROGRA~1\Zope1\lib\python\DocumentTemplate\DT_String.py, line 546,
in __call__
    (Object: ZDTopic_add)
  File C:\PROGRA~1\Zope1\lib\python\DocumentTemplate\DT_With.py, line 133,
in render
    (Object: ZDTopic.createInObjectManager(REQUEST['id'], REQUEST))
  File C:\PROGRA~1\Zope1\lib\python\DocumentTemplate\DT_Util.py, line 231,
in eval
    (Object: ZDTopic.createInObjectManager(REQUEST['id'], REQUEST))
    (Info: REQUEST)
  File <string>, line 2, in f
    (Object: guarded_getitem)
NameError: global name 'ZDTopic' is not defined

I would appreciate any suggestion to as what happens and how to fix it. I
run Zope 2.4.3 on win32 platform.
Many thanks for you help,
Agata