trailer 25 yards is to close. you should try aleast a 100 yards or more. at 25 yards the error will not show up very good.
I always start at 25 yards and get it dead on and then move out to 100 and go from there.
It is a lot easier to see what it's doing at 25 yards than 100 yards. JMHO ; just my 2 cents,there are 98 more