[mod_python] Cannot load templates using PSP class

In my python default handler, I am trying to load an html file in my 
code using the example below:

template = psp.PSP(req, filename='template.html')

The html file is located in the same directory as my .py file but this call 
fails unless I pass the full path of the html file in the call!

Any way to change this behaviour?

Thanks,

-Jalil