magnet sensor is not working. Display will not sleep

I can restate your question for you since I am having the same problem. My MacBook Unibody is also dealing with insomnia. When I close the lid, the display remains lit and operational as well as the keyboard backlight and this is clearly known due to the infamous Apple logo being brightly lit up.

I have replaced the logic board twice now (the first was semi-functional, the new one is fully functional) and neither times does the laptop sleep when the lid is closed. However, if I press the key combination Alt-Cmd-Eject, it will put it to sleep. I know the MacBook, any type for that matter, use a magnetized system to detect when the lid is closed and to initiate sleep mode. But I can't quite find the mechanism that detects that. The only place I can think it would be is either entwined with the battery indicator lights or built in with the IR sensor, considering that is where the sleep indicator light is. Any help would be appreciated for both of us. I am hoping it is a part of the battery indicator or IR sensor as that would make it an easy fix.

Thanks!

-Austin