Getting 0 pound postage when using a table rate.

[spikeycactus]

Hello, i am having huge problems with a 0 pound table rate issue on my
site at www.platinumhardware.co.uk
For some reason i am getting 0 pound postage when entering the final
stage of google checkout.

I have the following settings:

Shipping/Packing:
Enter the Maximum Package Weight you will ship 40 I
Package Tare Small to Medium - added percentage:weight 0:0
Larger packages - added packaging percentage:weight 0:0
Display Number of Boxes and Weight Status 3
Order Free Shipping 0 Weight Status 0 I
Shipping Estimator Display Settings for Shopping Cart 1
Display Order Comments on Admin Invoice 1
Display Order Comments on Admin Packing Slip 1

Table rate shipping settings:

Shipping Table
20:7.45,40:14.90,10000:0.00

Table Method
weight

Handling Fee
0

Tax Class
Taxable Goods

Tax Basis
Shipping

Shipping Zone
--none--

Sort Order
0

I have installed some other modules after installing zen cart, and im
not sure what files they may have replaced. Could you please let me
know which files carry the functions to affect the table rate
information.
Thank you, im in desperate need of help, this has been going on for
months now!