Dimmer switch replacing 3-wire switch not working
Your original is not a 3 wire light, but what amounts to a fan with a light kit installed. 

2 wires are for the light and one for the fan.

Generally they are wired WHITE - NEUTRAL to [FAN / LIGHT] , BLACK - HOT for [LIGHT] . RED - HOT for FAN. 

Is there another Switch on a different wall same wall that operated the original  Fan/Light Combination? 


This would tell us that the RED is a Traveler for a 3 Way Switch.


You will need to provide some more details:


Measure voltage between Copper Wire [GND] and WHITE.
Measure voltage between Copper Wire [GND] and BLACK.
Measure voltage between Copper Wire [GND] and RED.