Rats are afraid of new things. A trap placed in their path would be considered a new thing.
Here is a quick tip that will help you have better success with your rat problem:
Place the traps out for a few days but don’t set the trigger. Introduce food by putting some food on the trigger, but again don’t set it. When you notice that the rat is taking the food, re bait it and set the trap. It may take a few days longer than most people would prefer but trust us, your rat trapping success rate will increase and help you get rid of the rat.