I found the answer under this link
1.Shut down the computer.
2.Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
3.On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
4.Release all the keys and the power button at the same time.
5.Press the power button to turn on the computer.
I have the same model and I tested it. So in my case I had full charged the macbook and the led light from MagSafe power adapter change from green to orange.
When I had the same problem with you (with the led in magsafe adaptor not lighting) I solve it just with a pram reset. You can get info about how to reset pram here: http://support.apple.com/kb/ht1379