[mod_python] ob-CallBack Kenobi

This is an issue that seems to come up periodically on this list. I've 
searched and read all the messages I could find on the subject. The 
realy strange thing is that I've installed, setup, and used succesfully 
mod_python on two other NetBSD systems, with no problems. But the 
NetBSD system I'm trying to get it going on now (essentially identical 
to the previous ones) just refuses to cooperate:

make_obcallback(): could not import mod_python.apache.
make_obcallback(): could not call init.
python_handler: make_obcallback returned no obCallBack!

I've checked the permissions of the libraries, i've checked the 
locatoins, i've fiddled with the python path.

Can anyone give any more tips on how I might debug this situation and 
figure out what is actually going wrong here?

I'm using NetBSD 1.5.1, Apache 1.3.22, Python 2.01 without threads 
(installed in the standard NetBSD locations).