If the peanut ubettr you're using is kind of soft and spreadable , place it on the trip lever of the trap and then just allow it to sit without cocking the trap for a day or so, until the peanut ubettr gets a little stiff or hard. This will make it difficult for the mouse to lick it off without tripping the trap. Either that or use a piece of thread to kind of tie a piece of hard cheese on the trip lever so the mouse has to work to get the cheese for his last supper ! What I have done at least once to catch a difficult, i.e., a smart mouse, was to keep placing the baited trap in his area without actually setting it. You're actually feeding the little varmint for a couple of days until he's not afraid of going to the trap to eat. Then you bait the trap and cock the trigger on the third day and the mouse should set the trap off because he's used to it by now. Good luck! Hope you get that mouse!