The message could not be processed. This is most likely because the action ‘[Insert Web Service Action Here]’ is incorrect or because the message contains an invalid or expired security context token or because there is a mismatch between bindings. The security context token would be invalid if the service aborted the channel due to inactivity. To prevent the service from aborting idle sessions prematurely increase the Receive timeout on the service endpoint’s binding.
This is simply because SoapUI doesn't support security context tokens. Add these lines in Web.config:
Make sure that SoapUI has WS-Addressing set to true. Now you can test your WCF Service via SoapUI. However, you must be aware of the security implications using this approach.