Ok, I've tested it using EC2, and I am able to reproduce the failure you're getting. Using the table log component, configured to write to a log file, I was able to find the problem:
[[Schema Compliance]
No X11 DISPLAY variable was set, but this program performed an operation which requires it.]","11:10:47:837","Cancelling due to failed test step"
It seems that the soapUI Runner initializes the embedded soapUI engine as if though there was a UI, which causes some parts of it to fail if no UI is present. Since soapUI is designed to be able to run in a headless environment this should be pretty easy for us to fix. We just need to make sure to launch it in the correct mode. For now you can disable the "Schema Compliance" assertion and the test succeeds, but obviously that's not a very desirable solution, and other parts of your test may fail due to the same reason. I'll look into getting this fixed pretty soon. Thanks for providing us with enough information to locate the cause of the bug!
Regards,
Dain
eviware.com