Right the plot thickens... I have been bugged by your central locking dilemma and been doing a bit of digging and have discovered that there are 2 types of central locking aftermarket kits... the common one is the remote add on, which is for use with an existing system... I suspect that this is what you have, it relies on the system working and adds the lock / unlock signal to the original controller. The second type is usually found with a kit and it uses a 5 wire actuator to power the other locks... And this is the type of thing you need, unfortunately I haven't found one that isn't part of a kit...But I have found a kit that's silly money cheap!!
http://www.ebay.co.uk/itm/252688531620?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
You can use just the controller to get your system working and sell the actuators at $5 a pop and get most if not all your dosh back!
I'm not 100% certain that your controller is wrong as you haven't posted any pictures, HINT!!, But I'm 99% sure that the previous owner / muppet has tried to fit the common remote add on in place of the LR controler, which has left the system unpowered... there is also a way to overcome the problem with a series of relays, but that rather depends on your wiring skills!