USPS rate calculator wont work

[rd208]

I am very new at setting up a website. I need help getting this shipping module to work. Please can somebody help.

 

 

When ever I try to process an order the system fails. I get the following message:

 

This is currently the only shipping method available to use on this order.United States Postal Service

 

An error occurred with the USPS shipping calculations.

If you prefer to use USPS as your shipping method, please contact the store owner.

 

Based on searching the forum, I called USPS and had them transfer me to the production server but that did not help. I still get the same error.

 

USPS sent me the following info :

The URL you will use for the Production Server is:

Production.ShippingAPIs.com/ShippingAPI.dll

Where/how do use this?

 

Thanks