Central locking not working?

Ford Focus 99 T reg:The remote locking is not working, I am hoping thats just the battery. My problem is that when the car is locked manualy with the key I have to lock the passanger door seperatley because the central locking won't opperate properley, what could be the reason? or is this what happens when the battery stops working is there a remote motor in every door so if the battery goes in the remote all doors stop locking. I thought central was when the drivers door is locked by remote or by key motors in the other doors locked at the same time. If anyone can advise I would be very greatfull and thank you very much. Email at gary.comfort@tiscali.co.uk

Gary Comfort
November 2007