[Zope] ZCatalog & resource not found error

[Tim Moore]

This python script:

results = container.Catalog(meta_type='Broadcast',
                            getStartTime=DateTime(),
                            getStartTime_usage='range:min',
                            sort_on='getStartTime')

return results[0]

produces this error when I click the 'Test' tab:

Zope has encountered an error while publishing this resource. 

Resource not found

Sorry, the requested Zope resource does not exist.
Check the URL and try again.

If I take the [0] part off and have it return the whole results list,
I have no problems (it returns a list with two items).  Weird.

Any clues? (Zope 2.3.1 (binary release, python 1.5.2, win32-x86))
-- 
Tim Moore