[Zope] ZCatalog'ing nested ZClasses?

[Darran Edmundson]

I have a nested ZClass (Foo2) in a folderish container 
class (Foo1), ie.,

     Foo1Product
        Foo1Class
           Foo2Class

My problem is that Foo2Class's meta-type does not appear in
a ZCatalog instance's "Find items to ZCatalog" selection box. 
This is true even if the ZCatalog is created inside a Foo1Class 
instance.  However, if I select "All types" in "Items to 
catalog", Foo2Class instances *are* found and catalogued.

How can I get this nested ZClass to show up in the selection
box?

Cheers,
Darran.