[Zope] AttributeError __error_log__

Hi, I have a class which should behave like a simple folder. It uses a btree to store the values. I want to access it from a url like this: http://localhost:8080/myproduct/foo/myfolder/item1 If I try to access item1 I get the the folowing error: Module ZPublisher.Publish, line 150, in publish_module Module ZPublisher.Publish, line 114, in publish Module Zope, line 134, in zpublisher_exception_hook AttributeError: __error_log__ I tried to inherit from Explicit, Implicit or SimpleItem and even Zope2.6.2b3 This was discussed already but with no good solution: http://mail.zope.org/pipermail/zope/2002-December/127511.html Now I use BTreeFolder2, but I would like to avoid it, since I don't need most of it. Has somone a hint? thomas