By default, the flashlight is weak. To initially see the light, you may need to get close to a wall or object to shine it on.
If you have placed all the files in the proper folders (the best way to do it is to drag the files folder over the files folder in your program and allow it to overwrite) and are pressing the f key and still nothing happens, then re-read the instructions and try again from the beginning. You may have missed a step.
Does anything happen when you press f? Do you hear the clicking sound? What version of FPSC are you using? What other add on's are you using? What other info can you provide?
Best.