Okay, any more specific info?
Do you have the Directed display module? Is there a harness that came with it, or did you wire it up yourself? If you don't have the little display/control box, you need to use the Serial Port cable that MitchJS provides (or make your own, or whatever). That's what tells the unit to turn on.
Some more info will probably help get the correct answer to your problem. Be as specific as possible as to settings and wiring and stuff.