The error appears to be saying that you have not provided the service code. What value have you specified for this in your USPS shipping quote server behavior? This should be the first value in the interface for the Service Type.
Also, on the page that you are getting this error on please expand the bindings for the USPS values and find the full request and full response bindings. Place these on the page then test it again. This way we can see what was sent to USPS and the result they returned. Please post back with this info so that we can help figure out what is going wrong.