MacBook Pro retina not charging

I have a macbook pro retina 15" mid 2012 and it stopped charging. So thought the magsafe was broke. After changing the magsafe power supply the macbook worked well. I unplugged the charger when the battery was at 40%. After a few hours i tried the macbook but again the macbook wasn't charging. Macbook worked just till the battery died. Again i tried another magsafe without result. If i unplug the battery en try the charger the green light turn on off. No light when i connect battery and charger. What could it be?