Backlight not working, display does after changing hinges

Hello, mates

I've change the hinges of my macbook air a1237 (1,6ghz core2duo). After that when I power on the macbook I saw that the backlight is not working but the display shows the apple logo and it loads the OS. I've check the cable connections - everything is ok including cables condition. A month ago, I changed the lcd (defect) and after that everything works fine but now after changing hinges, the backlight of the display is not working. Keyboard backlight is working properly.

Can you give me some ideas to figure out where the problem lies on?

(i'm sorry for my bad english, i work on it)