locks, trying to install remote door locks.

[osofasts13]

well i just purchased a remote starter, installed it, no problem. now i'm trying to do the easy part, install the remote door lock. well obviously you buy a relay and splice it into the door lock wire and the actual wires that runs off the actual system activater. where i did it and nothing, it didn't work. well it did but it was wierd and ****, sometimes it will lock and unlock by itself. so i thought i'll take it to a professional to do it, maybe i'm doing something wrong, so i hook it back up stock and now the door lock mechanism on that side does not work anymore. you know like unlock the drivers door and passenger door unlocks too, now it only unlocks the driver side door, sending no signal to the passenger side. what's going on here??any body got any kind of experience with these systems?? i know they run off the single negative wire system...similar to the 300zx. i have a 91 240sx se. :help