Backlight not working after keyboard replacement

So I had this french keyboard which I just replaced with a qwerty us keyboard for my macbook A1261 - the backlight was working fine. Now it's no longer working - i've tried disconnecting and reconnecting the keyboard backlight ribbon and connector twice now...still not working...any idea what could be wrong? when i try to turn on the backlight on my keyboard the icon is greyed out and crossed as if not available...