Trials Evolution

I converted a boat trilear into a utility trilear.There is a green and brown wire operating down the appropriate side.There is a yellow and brown wire operating down the left side.Each wire is meticulously soldered and shrink tubed.There is a white wire (ground) connected to a ring connector and soldered. It's attached to the trilear with a screw. I sanded off the paint to expose bare metal.The lights will not work.I'm quite confident there are no cuts or discontinuities anywhere.What I feel is the problem is that I screwed every single lamp in the back again to an angle iron. The angle iron is screwed to wood.So, is that messing issues up? Do the lamps have to be screwed to real metal of the trilear for appropriate grounding?Any ideas would be drastically appreciated.