Error response SOAP

Dear,

I've a XI to SOAP sync scenario. My problem ocurred when i send xml to web service.

In SXI_MONITOR I can see that message arrives to the web service but in the response returns a error (without payload).

The mapping logic is very simple. In outbound process only assign a constant to consume the web service and in the response I using XSL mapping:

This is de web service request:

And this the response:

And ack:

I have checked the web service with SOAPUI and it returns response correctly.

I have seen similar discussions but i don't see nothing clear:

SYNC SOAP scenario: Can't parse the document; HTTP 200 OK

Can't parse the document; HTTP 200 OK

Any idea?

Many thanks,

Regards.