switch wiring

I'm trying to replace an exterior fan with a light. Where the multispeed fan switch was there is just a black and red wire. Where the fan was is a black, red, white neutral and green. The only way I can get the light to turn on is hooking up the black and neutral at the light, but then I can't turn it off. Since I've got black and red at the switch I hoped that black and red at the light would work, but it demands neutral to light up. I've tried multiple combinations and can't find one that works. Black and neutral at light = constant on even when switch is off. Any other wiring combo, including black and red at both switch, and light doesn't work.