Debug mock services generated by soapUI

Hi.

preconditions:
1. response(generated as mock service) in soupUI
2. web-client, that knows about running mock service by address:

http://localhost:8091/axis2/services/

Mock services are running OK.
When perform request from web-client,I expect to get response as specified in soapUI.
Instead of this I got general error:

    org.apache.axiom.soap.SOAPProcessingException: First Element must contain the local name, Envelope , but found html

That means there are problems with response,thus html with 500 code returned.
How can I debug what is the cause of problem?

thank you for help.