Okay, here goes:
After renewing the transmitter battery, the infrared transmitter must be initialized.
The same applies if a new transmitter has been obtained.
close the drivers door, briefly turn the ignition key to position 1 in the steering lock and turn back to 0.
press button 1 (unlock button) on the transmitter and hold depressed. Press button 2 (lock button) briefly three times within 10 seconds, meanwhile keeping button 1 depressed.
Release button 1; the LED will flash slowly for max 10 seconds.
hold the transmitter close to the receiver under the inside mirror (at a distance no more than 15 cm) and press button 2.
The central locking function will be engaged and immediately released again, indicating that the transmitter has been successfully initialised. If the LED does not flash or if the central locking does not respond, the initialising procedure must be repeated.
any other transmitters used for the car must each be initialised within 30 seconds. do not operate the ignition at this time.
Hope it helps.