It says that "Almost every list, button, knob, and slider in MixEmergency can be mapped to a MIDI controller - giving you hands-on access to the functions most important to you. It's flexible, powerful, and easy to set up with the built-in MIDI learn capability. In addition, MixEmergency's MIDI output enables you to provide feedback directly to your MIDI controller; so you can light your controller's LEDs and meters." How can I do this? I've got two midi controllers and neither of them lights up.