I have found trailer trailer wiring kits to have different wire colors coming out of the light assemblies at times. One kit I bought had a green, a white and a black wire from each light. The green was the side marker light and tail light, the white was the stop/turn light and black was ground.

That assembly is on the shelf over my head - never used that kit.

The kit on my 5x8 trailer uses white/black/yellow from the assembly.

Now, are your lights used or new? If used, the sockets could be so corroded that WIRING is not the problem, the sockets are! If THIS is the case, you can screw around all day and not get anywhere!

YOu can temporarily turn on the parking lights, have the side markers come on, and then use that hot lead to experiment with different combinations of the wires coming out of the light assemblies and therefore identify what is what. Take the lenses off so you can see WHAT element in the light comes on.

Remember, the smaller element is the tail light, the brighter one is the stop/turn.