First make sure that your MIDI controller is recognized and assigned to the main controller parameter.
Simply navigate to the Layout Mode and click on the Keyboard graphic. Then click on the assign button and it should light up red now letting you know you are in assign mode. Then tap a few keys on your controller and the device should now be synced.
Click on the assign button to disable assign mode and then go back to the edit or perform screen. You should now be able to hear sound as you play your MIDI controller.
If you still have questions or need further assistance please contact our support team.