Import - interpreter works but .py import does not

[John Boy]

First post and very much a newbie to Python. Have 2.5 on Linux (GG). I
think I have set up PYTHONPATH correctly in that I can import a module
apply_bp and it complains about line 20 in apply_bp which is:

import sys, aipy, numpy, os

At the interpreter prompt, however, I can import sys, numpy etc. and
can do dir() and see the entry points so I think my overall
installation is OK.

Why does line not work ? Also I would have thought that when I pre-
imported sys et al that they would be in the symbol table so that the
import line would be a noop.

          Thanks,

                     Slainte,

                                John