Backlight doesn't work after replacing inverter.

The backlight blinks on start up, but fails to illuminate the screen. To test as whether or not it was the bulb or inverter, I hooked an inverter from another laptop to the bulb and confirmed the backlight worked. I then bought a new inverter and replaced the old one. Still I have the same problem, I checked the cable with a meter and had continuity across all 4 wires. I checked voltage and found 5v on the first wire, 3.5v on the second, gnd on the third, and 12v on the fourth. Anyone else have any ideas. Thanks