Do you have an un-altered "Try Me Button" that you can plug into a prop and see if it works? How long is the wire from the fence to the prop and what gauge wire are you running? Will the prop trigger with the un-altered "Try Me Button"? Without knowing anything else, I'm leaning towards the resistance of the wire being too high for the voltage being run through it. Simply, every wire has resistance. If the voltage isn't high enough to overcome this resistance, you're prop will not run. Based on the guage of wire you use and the metal type, a calculation can be made to determine the greatest length of wire that can be used. This would not take into account for degrading batteries. Let us know some more info and we'll try to give you some ideas.