[Zope] First attempt at writing External Method .. need help

Howdy, I wrote the example as in The Zope Book; file hello.py in Extensions dir def hello(): return "Howdy there big world" I created a folder testExternalMethods and added External Method = hello ... It added with no errors, however clicking on the 'Test' tab of object 'hello' does nothing and the URL testExternalMethods/hello produces a blank page What am I missing here? Thanks, Kent