Update...
I updated my USPS username as you directed. How I can getting an error code saying the it cannot connect to USPS.
I used two types of testing server addresses that USPS provided me:
1. ShippingAPITest.dll
2. ShippingAPITest.dll
The first testing server address produced an error that stated my username was incorrect. The second produced an error that stated that it could not connect to USPS.
Any thoughts?