Hi Pavel,
You can get this error if the xml message you send to the webservice isn’t matching the xsd schema in the webservice.
It can also be a problem with security. This occurs when the account in which the webservice runs doesn’t have access to the BizTalk database.
That you don’t see anything in the HAT means it didn’t get from the service to the MessageBox database, which won’t happen in the above scenarios. I’ve never met a situation where I got a message in BizTalk after getting a SOAP exception.
Hope this helps
Eli