Need help installing keyless entry

So I picked up a cheap keyless entry system off EBay. I know why it was cheap now. No install instruction s came with it. WTF?

So I trial and error'd it and thought I had it all working, that is until I clossed the door.. Unit works perfect when i have the doors open but stops functioning as soon as they're closed?

Any body have a though as to what I may have done wrong?

I have hooked up: Positive + Negative at the Ign switch. Parking lights at the back of the fuse box Green wire in 12 pin connector. Then lock and unlock (grey + purple) from the 22 pin connector at the fuse box and then trigger on the green wire.