Go back to using the production URL and contact USPS, they will need to authorize you;re account to access the production server.
Thanks for your help on this manner.
I have it working. Here is what I found out. Just creating an account on USPS isn't enough. In order to make the USPS shipping feature work with eCart 5 you must:
1) Create an account with USPS
2) Go to webtools/
3) Sign up to access USPS web tools.
4) Once you sign up USPS will send you an email with a password and username.
5) Call USPS at 1-800-344-7779
6) Give the rep your username.
7) The rep will ask if you are using a 3rd party.
8) You will receive an email accepting your move to production.
9) On the Webassist screen put in the production server address supplied in the email and also your new userID given in your acceptance email.
Thanks for your assistance.