Australia Post Extension - The basket weight is 0g Error

Hi, I've recently installed Australia Post extension for version 1.5.1.3 of OC. Unfortunately very often I have an error on checkout saying: "The basket weight is 0g, unable to calculate shipping costs" which is not true (products and weights have been configured properly). Any ideas where could be a problem?

Did anyone reply to this as I am getting the same problem

All good, latest Aust post extension fixed this