Compaq v2000 function key not working?

Question

My compaq v2000 function key seems to be not working.Pressing Fn F8/F7 to control brightness -not working but can alter screen brightness through control panel. Also scroll/number lock light not working. Keypad works fine in my compaq v5000 and swapping keyboards makes no difference as same problems persists. Could this be a motherboard problem as have recently had replacement motherboard fitted to v2000 and has only materialised since.