line tracker calibration

Hi, can anyone tell me how to modify the 2011 kop line tracker to detect grey tape because I read a pdf file for it and im confused. As of now the line trackers starts as green then when I pass it over the reflective only, it turns orange and yellow.

There is a little slot on each line sensor where you can insert a small screwdriver. Turn the screwdriver until the light just changes color, and then turn it back a bit so that when the sensor goes over the differently covered tape it will change.

Refer to this thread.