I installed a light fixture in my den. There was already wiring in the ceiling box and i want to control the light via a wall switch. There was a red, white and black wire in the ceiling box. My fixture only had a black and white plus a copper ground wire. I tied the red and black wre from the ceiling along with the black wire from the fixture. I tied the white wire from the ceiling to the white wire from the fixture and tried to use the light. It is always on and doesnt operate with the wall switch. I untied the red wire from the blackIwith no change. I looked at the wall switch. It is a basic on/off switch with a black wire in the top position and a red wire in the bottom position. I cant figure it out. Why wont the switch operate the light? For your info, the house is 3 years old and was already prewired.