Hi I have just installed a new head unit into my 2000 r34 skyline. Everything works well. But I have also installed sub and amp. Its has power on amp new wires...power earth remote and rca cords. But sub is not working. Am I missing a wire that needs to be hooked up? Theres only 3 wires not linked to anything thats on a individual plug...they are...GREEN...RED WITH BLUE STRIPE...AND BROWN WITH BLACK STIPE...anyone have the same issue?????