How can I reprogramme my key fob for a ford focus 02 tdci ? (continued)?

Put a brand new battery in key fob so it wasn't that. key starts engine okay but won't let me open the central locking via the key buttons. Followed instructions for 01 model but the led light doesn't stay on for the 20 seconds as stated.
Thanks Dave, tried turning key on/off 4 times and in ignition, heard a chime, pressed remote control on then off again, but alas still didn't work. Anymore ideas?