I have been playing with this problem for a week. I have a 3-way switch with the power source which then goes to two can lights then to another 3-way switch. I am trying to add a light after the second switch. Ideally the new light would be controlled by a second switch, but I can live with all the lights being controlled by one switch. The biggest problem is that I cannot access the can light to actually see what is going on. Each time I try to add the new light the best I can do is to get all the lights working at half power. How can I get this to work?