golf mk4 remote locking?

i have just bought a mk4 golf gttdi 130 and the drivers door does not unlock with the remote works fine with the key if you press the remote once alarm disable but nothing happens if u press twice all other doors open i was told the previous owner had the door disconnected as they were worried about the auto lock and leaving there key inside. so how do i go about reconnecting the door as it is very annoying.