[Zope] Newbie Question : Problems with Automatic Cataloging of ZClasses

I wonder if someone could help me. I have been trying to create zclasses whose objects get automatically catalogued. I have followed the tutorial in the Zope Book (Chapter 9 - 'Automatic Cataloging' section) and it all seems to work correctly. When I go and view the entries in the catalog however, only the date gets registered in the index, and date and absolute_url gets registered as metatypes - no other properties appear to be registered. I have tried other tutorials and HowTos but cannot seem to find an effective way of updating a catalogue with all the objects properties. Could someone give me a clue