Shipping Error

I'm working on an ecomerce application (who isn't these days) and I've installed and configured the only shipping mod I am aware of (http://shipping.rubyforge.org/). In all of the examples it works like a charm, but I can't seem to get it to work correctly. To test the install I'm running the following lines through the console:

require 'shipping' ups = Shipping::UPS.new :zip => 97202, :sender_zip => 10001, :weight => 2 ups.price #which returns 0.0

ups.response => "UPSOnLine5%Missing ActionCode%6837\n"

I've scouted around online, but can't find anything that tells me why this is happening or how to fix it. I'm probably missing something obvious, and would appreciate a little enlightenment.