Try again, but this time make sure no spaces or extended characters are used. That way, you need no quotes. Also, what version MobideDRM.py do you have? if you have 0.02, it could be that you need 0.01. If you have 0.03, it could be the bug has gotcha and you need 0.04, 0.02 or 0.01. If you have 0.04 then I have no idea the problem as it works for me.
What version Python do you have? Did you get Python from
http://www.python.org?