Sorry, we are not shipping to your region at this time.

This message usually occurs when you have no available shipping modules for that customer's address.

A module is unavailable for one of two reasons:

1. it's not installed
2. or it's installed but has a Shipping Zone restriction set on it, and the customer's shipping address isn't in that specified zone.

Or maybe the order qualifies for Free Shipping, but you don't have the freeshipper module installed.