@Override
	public void onTrackerStateChanged(int trackerState) {
		trackeStateOK = false;
		String errorMessage = "";

		if (trackerState == 0)
			trackeStateOK = true;
		else if (trackerState == 1)
			errorMessage = "Device not connected.";
		else if (trackerState == 2)
			errorMessage = "A firmware updated is required.";
		else if (trackerState == 3)
			errorMessage = "Device connected to a USB2.0 port";
		else if (trackerState == 4)
			errorMessage = "No data coming out of the sensor.";	

		System.out.println(trackeStateOK + " --> " + errorMessage);
		if (isAborting){
			StopAndClose(errorMessage);
		}


		if (trackeStateOK == false){
			// Lost device, abort calib now (raise event)
			AbortCalibration(errorMessage);
		}		
	}