High Cathode basically neons, wiring Options

[Etak28]

I wired up four high cathode aka almost the same as neons to my car. They all run up to two switches near my dimmer light and then to my battery. The front two work great but the back two won't light up fully. I dont know if its the wires or if its because only one power line was ran or something. I need help so instead of three to three and a half neons i have four. Does anyone know what the problem is: wiring or am i not getting enought power.