congrats, trace! a track at your set is evidence of doing everything right. sometimes they are just not interested an move on. If you can keep 'em there a bit, you up the chances of snagging one (i.e. make em dig at your bait at dirtholes, make em pee on your post sets, etc.) its that extra bit of attention they pay at your sets that causes a few extra foot steps. Remember, control their nose, and you control where their feet go.
Jim