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.