[Zope-CMF] Monkey patching doesn't seem to work

[suresh_vv]

I want to make PortalFolders searchable.

So:

1. I created my version of MyPortalFolder.py in MY products directory,
2. imported the CMFCore version of PortalFolder
3. wrote a function mySearchableText
4. Set PortalFolder.SearchbleText = mySearchableText
5. imported MyPortalFolder.py in MY __init__.py
6. Restarted Zope

No improvement. But if I change the PortalFolder.py in CMFCore 
directory, it works!

Why cant I make it happen thru the "magic" of Monkey Patching? 

So I can easily upgrade in future.
I got the idea from a HOW-TO in "Caseman"'s home page.

Thanks for any help.

Suresh