So apparently only specific transactions can be made using the testing API. I wrote to USPS for approval and since I'm using a 3rd party software there is no need to test...perhaps this should be documented in the getting started guide.
Anyway I now get this error:
2147219428DomesticRatesV3:clsRateV3.ValidateFirstClassMailType;RateEngineV3.ProcessRequestInvalid First Class Mail Type.1000440