HI there ,sounds to me you are not entering the code correctly, first you turn the ignition on then the led should flash fast, then you need to count the the led flashers for how many times the first digit of the code is by pressing ,and holding the central locking button,so if the first digit is example 2 you press and hold the central locking button for two flashers of the led, then you let go of the button, then press and hold the button for the next digit ,when you have entered the four digits if the code is correct the led will stay on if it flashers either the code is incorrect or you have not entered the code correctly,if the light has stayed on after the code has gone in,then you need to remove the key ,point the key at the reciever in the roof and press the plip 3 times this has to be done fast,if the plip did not program ,if you put the key in the ignition the engine will start ,if there is nothiing else wrong.
mark
December 2008