Fix Cubecart v3 USPS shipping issue

Using v3 (free version) of Cubecart. I am trying to use USPS first class mail. I have walked through the tutorials and setup my usps web tools account, however I was getting an xml error: Request XML:<RateV3Request USERID="-#" PASSWORD="#"></RateV3Request>Return XML:<?xml version="1.0"?> <Error><Number>-2147219085</Number><Source>Rate_Respond.;SOLServerRates.RateV3_Respond</Source><Description>Invalid XML Element cannot be empty according to the DTD/Schema. line= 0 pos= 1196</Description><HelpFile></HelpFile><HelpContext>1000440</HelpContext></Error> Now shipping is not showing up at all. Need someone familiar with Cubecart to fix this.