I'm not sure you are doing something wrong as much as running in to a limitation of the simulator. Your circuit looks fine, I suspect the problem is trying to simulate the analog portions of the code. The simulator doesn't have a way (without a lot of complex additions) to know what the value of the analog voltages on the pot and the ldrs are is I suspect the problem . For that you may have to try it with actual hardware, simulation can only take you so far 
Peter