Why are the shipping cost for google checkout less then the store returned ones ?

Why are the cost for ups shipping less on the google checkout page then the returned calculated shipping cost on the 1st page of my stores checkout ?

example :

My store returns the shipping cost for ac adapter as

United Parcel Service (1 x 1.50lbs) United Parcel Service
$11.17
Ground

Google checkout shows the cost as

ups ground $8.41

This Google checkout quote seems right. Is there a setting i need to change in admin ?

What are your settings in the Configuration ... Shipping/Packaging ...

First off thank you so much for replying to me. Here are my settings for that section. I hope i got back to you in time

Enter the Maximum Package Weight you will ship
20

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

Shipping Estimator Display Settings for Shopping Cart
1

Display Order Comments on Admin Invoice
1

Display Order Comments on Admin Packing Slip
1

What are your settings on the Modules ... Shipping ... UPS shipping module?

You may need the UPSXML from the Free Software Addons to get the lower rates with your account ...

UPS Pickup Method
CC

UPS Packaging?
CP

Residential Delivery?
RES

Handling Fee
0

Tax Class
--none--

Tax Basis
Shipping

Shipping Zone
--none--

Sort order of display.
0

Shipping Methods:
Nxt AM, Nxt AM Ltr, Nxt, Nxt Ltr, Nxt PR, Nxt Save, Nxt Save Ltr, 2nd AM, 2nd AM Ltr, 2nd, 2nd Ltr, 3 Day Select, Ground, Canada,World Xp, World Xp Ltr, World Xp Plus, World Xp Plus Ltr, World Expedite, WorldWideSaver
GND, STD

did i mess something up there ?