USPS Shipping API Error

I'm testing out my OC site and my client is going to use USPS Priority Mail.

The account has been created with shippingapis and I have not called them to move me to the production server. I've edited the url to the test server and am getting the following error:

API Authorization failure. RateV4 is not a valid API name for this protocol.

Any thoughts? All of the information in the shipping module is correct.