Problem from PI to SAP system

The error from PI when the try to send to SAP system is:

transmitting the message to endpoint http : //xxx.xx.xx.xx:50400/sap/xi/engine?type=entry using connection jdbc_http://sap.com/xi/XI/System failed, due to: com.sap.engine.interfaces.messaging.api.exception.MessagingException: Received HTTP response code 404: Not Found

Can someone tell me where to look?

Thanks

PS Where Can I change the port?