Under certain circumstances of normal operation, none of GiO’s lights are illuminated.
In order for GiO’s Stompbox Indicators to light, the track onto which stompboxes have been inserted must be selected.
If you’ve selected a track with no stompboxes, the Stompbox Indicators go out.
If you have selected a track with stompboxes in Logic 9 and GiO is still not lighting up, go to the Logic Pro menu > Preferences > Control Surfaces > Setup. Select the GiO icon by clicking on it. Press delete. Quit Logic and then relaunch it.