Error Message during Shipping Extension Installation

I've installed my shipping extension and will only be using the U.S. Post Office to post my parcels. I've acquired a USPS Webtools Account and have followed the instructions for installation as provided in this link...

viewtopic.php?f=142&t=30713

However, when I test my website I receive the following error message: "Authorization failure. You are not authorized to connect to this server."

My first thought is that the problem is most likely that my current domain is alive and I'm building my new opencart website on a new, different domain. When I assigned my domain to the USPS Webtools Account I used my new opencarts domain instead of the live domain.

What do I need to do to get my shipping extension to work, so I can test it?

when you first create a usps account you are on their "test" server.. so either choose the test server in the usps module config or call usps and tell them you are using opencart and need to be switched to the live server

I received three test server addresses from USPS, shown below, but am not sure if it matters which one to use. I'm also unsure what I need to do with the xml string to integrate it.

Your Web Tools User ID is required to test and integrate USPS Web Tools APIs. With this ID, you may begin sending calls to the test server. Depending on the API, the address to the test server is either http://production.shippingapis.com/ShippingAPITest.dll or https://secure.shippingapis.com/ShippingAPITest.dll. Use this information in combination with your User ID and your XML string to send a request to the USPS servers.

What exactly do you mean by 'module config?' I'm not sure whether you're talking about a config.php file on my server, a place in the admin extension/shipping module for usps, or that there was a place on the usps website to choose when I signed up...

I've been working with a very helpful postal clerk, trying to get beyond the error message I keep getting when testing the integration of the USPS shipping module into my website.

The latest error message reads..."Warning: No Shipping options are available. Please contact us for assistance!"

I requested to be moved to the post office's live server, which has been granted. The clerk informs me she "did confirm that the permissions are all in place so if you continue to receive error messages, there may be an issue with coding and we are unable to see the back end of the account. You may have to contact the vendor of your software to troubleshoot coding issues."

I'm using opencart v.1.5.6 and don't see any place in the usps module config to choose any type of server. What else might I be doing incorrectly that is preventing me from getting the usps shipping module to correctly integrate into my website?

enable debug on the usps module and check the system error log for the data being passed back.

Okay, I've implemented a debug, and created an error log.

I've gone back into the usps shipping module and have selected all available services, for both domestic and international shipping. Previously I had only selected First Class Parcel.

The module appears to be working, but it's not providing First Class Parcel pricing. It's only giving me prices for shipping via Priority Mail.