[Zope-CMF] how to create an indexed attribute programmatically?

[Gerry Kirk]

Hi,

In reading the source in PluggableIndexes/common/Unindex.py, and 
CMFCore/CatalogTool.py, I should be able to create an indexed attribute 
by the following:

catalog.addIndex('indexname','indextype','attribute_name')

It creates the index, but the attribute is not indexed. I want to index 
Title so I can sort on it:

catalog.addIndex('Title_sort','FieldIndex','Title')

I can do this through the ZMI, so I'm not sure what is different here.

TIA,
Gerry