v139h USPS Flat Rate Boxes Problem

Having problems getting the USPS module to display the correct options for flat rate boxes. I have enabled Medium and Large flat rate boxes in the config and set the Packages Dimensions Config to:
11x8x5;5
12x12x5;14
regular;+

What I want is for shipments with a weight of 5lb or less to go medium and 5-14lb to go in large box. During checkout, for an order with weight of 13.13lb, it gives option for both medium and large boxes.

It appears that no matter what the weight is, both boxes are listed as shipping options.

I'm using Zen Cart 1.38h and USPS Shipping Module 1.21

Thanks for any help!

Tony Spradlin
www.peppertraders.com