MacBook - Macbook screen does not turn on with battery power

Hi, I have a Macbook and the screen will not turn on when the battery is providing any power. The screen flashes a loading screen then acts as if the screen is asleep (caps lock, cd rom, num lock all working and active). When I remove the battery and run only off AC power only the computer works fine. With AC power and battery in place the screen will not turn on. So I know my screen is fine and the battery is fully charged. Any suggestions how to fix it? (I have reset the computer by taking battery out and holding down power button for 10 secs, no help) Thanks in advance!!!!!!