Issue with Axis reciever adapter :SAX Parser excepion in response mapping

Hi Experts ,

We are facing an issue while trying to consume a rest servcie via axis reciever adapter using the below blog:

https://blogs.sap.com/2012/08/11/calling-synchronous-restful-web-service-with-pi-i/

Our sync scenarion was like below:

SAP CRM<->PI<->Rest service

But while testing the scenarion finding an exception:

Transmitting the message using connection SOAP_http://sap.com/xi/XI/System failed, due to: com.sap.engine.interfaces.messaging.api.exception.MessagingException: Error encountered while executing mapping: com.sap.aii.af.service.mapping.MappingException: Mapping failed

while checking with reciever team they confimed there was no hit from PI at their end .but the request hits to that server via firewall and from network end the communcation is fine.

Can you please suggest why the invalid response is fectching and the rest service is not getting triggered from SAP PI .Thanks in advance!