[Zope] Creating CatalogAware products.

Hi all, First time poster, long time lurker.. Ive been trying to create a product which is CatalogAware, with only some success. * I have a ZCatalog in the root of the zope installation called 'Catalog' * The class for the product inherits/mixes like thus: class myProduct(OFS.SimpleItem.Item, Persistent,.... Products.ZCatalog.CatalogAwareness.CatalogAware): * In the __init__ method, I have : self.index_object() * In any method which modifies any of the fields that are used as indexes in the catalog I also have: self.index_object() My problem is, The products will not add/delete themselves from the catalog, but when I modify the item, the catalog is updated. What am I missing about this? Regards, Adam