Interesting, I work on the exactly same scenario and it works like a charm. I'm even also using 7.1.1.
Did you check if the deployed mdb2.jar was packaged correctly, and it contains the classes on the appropriate structure?
I've created some small projects which only cover the described scenario and it works!
The problem was a missing linebreak after the "Dependencies: deployment.mdbbase.jar".
Thanx a lot for the response.