Maybe 1 of the 2 connector cables from and to the main board not put in properly or the iron flat pins on the back of ur screen needs to be raised a fraction more, i had the same isiue, and solved it by reconnect cables and raised pins, be carefull not to force any action, goodluck.

i used this youtube link to replace mine http://www.youtube.com/watch?v=9dxsTGpGRhs