checkoutapi

One of the Ecommerce sites I am building cannot ship to several states as they don't allow alcohol to be shipped in for various legal reasons, so I am trying to prevent transactions with a shipping address in one of those states from being completed with a checkoutapi hook.

Unfortunately, it doesn't seem to kick in when I try to checkout with a shipping address from one of these states - it lets me continue on to Paypal. Where am I going wrong?

<?php

/* Implementation of hook_checkoutapi to make sure we don't ship to Mass, Pens, and Utah */