Night Service Button

Question

I have the Avaya 4424LD+ phone console. The night service button does not seem to be working properly. When I hit the button it lights up, but should anyone use the phone during the evening it goes off. "Press Line/Feature Button Inspect Mode comes on the display. What does that mean? I can't seem to find the Inspect Mode button and either turn it on or turn it off. HELP!! Also, I can't seem to turn off the privacy button.
Thanks