NuForce uDac-3 not working

Just configured Volumio and my NuForce uDAC-3 is not recognized. I also have a uDAC-2 that I use in my media server (OpenELEC) that worked without problems, but the uDAC-3 does not work in OpenELEC either. Any ideas? (just in case, the uDAC-3 works fine in my Mac).

Best, Gerardo