I have a problem with one of the remote key fobs on my Rav4.1. Ihave put numerous new batteries in it but it will not engage or disengage the central locking system on the doors. I have checked it with my spare and everything seems ok. The led light does come on and off when I depress the open and shut buttons on the fob. The spare one works OK thank goodness Ireally would appreciate some help and advice on this one.