316i compcat central lock

i had an aftermarket keyless entry and i want to install on my car 316i compact 1997 german spec. i knew that bmw had single and double locks. I opened  the glove  box   to locate the central lock but there's no 12 pin connection so the car was not pre-wired for alarm\keyless entry. There's a black box connected by 3 connectors. I think the 26 pins pur\yel connector was for central lock and i was right. to determine the lock and unlock signal i disconnected  the 26 pins pur\yel connector and test each 26 male pin that connected to the black box, I found pin 17&19 for lock and unlock but this for single lock only even i used diodes never double lock and later i found pin 16 & 3 for lock and unlock signal to   make the the car double lock. But the problem is when i tapped the lock and unlock wires of the keyless enrty to the wire of pin 16 & 3 and connect the connector to the 26 male pin of the black box and press the lock\unlock button of the keyless enrty the car never lock and unlock. is there anybody can help me to find double of this car?    tanx

ps pin 17&19 have existing wires unlike pin 16 & 3 nothing