Hi chinamox,

I fully agree with davorg on the indentation tip.

Secondly, you didn't say how you're calling the program.  I've tried to guess what your arguments are, but it "works" (comes back to the command-line) for me every time.

A simple way to debug is to sprinkle print statements throughout, and see which ones get executed and which ones don't.  I always use something like:

print "TFD> [1] Got here\n";
[download]

to tell me I got to a certain line.  The "TFD>" stands for "temporary for debug"; so I can take all the debug lines out later.

Hopefully that gives you a good start in finding your problem.

If not, please give us more specific information about what your command line looks like, and what your input files look like.