Apart from what chromatic and splinky have said, one thing that strikes me as possibly wrong (but not related to your question) is the lack of quotes around the subject. I'm not familiar with quoting rules in DOS/Windows, but it may be better if you assign like this:

$subject='-s "Your Nexis Universe ID"';
[download]

so that the whole string is considered as the subject and not only "Your".

--ZZamboni