tells reason
 

Should attract but do not it respells why?

If you cut a magnet in half, the newly cut faces of the magnet will become the new north or new south poles of the smaller pieces. These smaller magnets will attract each other. However, you only get two magnets, if you cut it gently. The magnetic domains in a magnetic material can be knocked loose, by vibrating the magnet (like when sawing it in half). If knocked loose, the domains are no longer arranged neatly, so they do not reinforce each other. If they are in a random orientation, with their fields pointing all over the place, they repel each other.