post back the full request and full response so we have a better understanding about what is failing in order to give advice on how to fix it.
I added the full error description to the page. The error message I get is
80040b1a Authorization failure. Perhaps username and/or password is incorrect. UspsCom::DoAuth
I have double checked my username and it is correct. I don't find a location to enter a password for USPS.
The only fields asked are userID and then there is an xml server address. The address listed in my program is shippingapi.dll