I am installing a light fixture to a fan with no blue wire. instuctions say red to red, black to black, brown to brown. all these wires go to fan speeds. The light fixture only has a white and black wire. instructions say connect white to grey, which is hot, and black to red. problem is that the red is used for fan speed, and when I connect to red wire, the light goes off, and then dim, when I run the fan through the speeds.