it appears that you may not even get that message out to us due to a cert issue. In fact it is not finding the cert probably (u201CNo trusted certificate found # nullu201D).
IDoc processed successfully through XI prod but there is error in processing through AS2 (BIS6).
Error : javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: No trusted certificate found
Ask your BASIS team to check deployed AS2 certificate of your customer on PI Prodcutions server. If this is FIRST AS2 message you are sending to your partner means the AS2 certificate is not yet deployed on PI server. If it is not,The certificate may be expired and that needs renewal. So ask your AS2 partner to provide valid Production AS2 cert. and ask BASIS to deploy the same.
Once valid certificate deployed check your config once and try to resend the message from Adapter engine.