UPS Shipping Works but Inaccurate when Shipping to USA from Canada

[soma57]

Zencart Version: v1.3.8a
UPS Dimensions Support Module Installed
Problem: UPS quotes are sometimes inaccurate

Greetings fellow Zenners. I have successfully connected my UPS account to my store. Using the XML plugin I can dynamically grab rates directly from UPS. I am able to get identical quotes from the store and the online UPS website....for the most part.

What works:

From Canada to Canada
Weight: 60 lbs.
Dimensions: 20 x 20 x 20 (in)
Prices are accurate on My Store and UPS Online Shipping calculator

From Canada to Canada
Weight: 20 lbs.
Dimensions: 20 x 20 x 20 (in)
Prices are accurate on My Store and UPS Online Shipping calculator

From Canada to USA
Weight: 60 lbs.
Dimensions: 20 x 20 x 20 (in)
Prices are accurate on My Store and UPS Online Shipping calculator

What doesn't work:

From Canada to USA
Weight: 20 lbs.
Dimensions: 20 x 20 x 20
My Store Standard UPS Shipping Estimate: $52.47
Online UPS Shipping Estimate: $105.52

This is obviously an issue with weight. Again, everything is otherwise accurate except where the weight is lower compared to the dimensions and being shipped to the United States. Where a product is weighs less the shipping prices seem to go way off.

My Settings:

Modules > Shipping > United Parcel Service (upsxml)

Enable UPS Shipping
Do you want to offer UPS shipping?
>> TRUE

Pickup Method
How do you give packages to UPS?
>> DAILY PICK-UP

Packaging Type
What kind of packaging do you use?
>> CUSTOMER PACKAGE

Customer Classification Code
>> 01 (If you are billing to a UPS account and have a daily UPS pickup)

Shipping Origin
>> Canada Origin

Origin City
>> Mississauga

Origin State/Province
>> ON

Origin Postal Code
>> L4Z1M1

Test or Production Mode
>> Production

Unit Weight 
>> LBS

Unit Length
>> IN

Quote Type
>> Commercial 

Handling Fee
>> 0 

Enable Insurance
>> FALSE

UPS Currency Code
>> CAD

Tax Class
>> NONE

Shipping Methods
>> Next Day Air
>> 2nd Day Air
>> Ground
>> Worldwide Express
>> Standard
>> 3 Day Select

Shipping Delay
>> 1

Configuration > Shipping/Packaging

Country of Origin
>> Canada

Postal Code
>> L4S1M1

Enter the Maximum Package Weight you will ship
>> 50

Package Tare Small to Medium - added percentage:weight
>> 0:0

Larger packages - added packaging percentage:weight
>> 0:0

Shipping Delay
>> 1

Display Number of Boxes and Weight Status  	
>> 3
 
Order Free Shipping 0 Weight Status 	
>> 0 

Shipping Estimator Display Settings for Shopping Cart 	
>> 1 

Display Order Comments on Admin Invoice 	
>> 1 	

Display Order Comments on Admin Packing Slip 	
>> 1

Note: Although I've inputted 20 lbs as the product weight through the UPS online shipping calculator when I receive my quotes there is a field under each estimate that says "Billable Weight 49.0 lb". That being said there seems to be a problem where light weight packages being shipping to the United States - but why wouldn't both the store and the UPS website reflect the same shipping estimate price in this regard?

Any suggestions would be greatly appreciated.

[soma57]

Does anyone have any direction on where to take this or what I can do?