Is the ledge locking into place after you use the spinner? If it hasnt locked it will just fall back down. Keep spinning until it locks in place. Walk right up to the ledge, it should be right above you and a little to one side. Just doble jump straight up and move a little forward to land on the ledge. Maybe you are looking at the wrong edge, or trying to jump from too far away? It is right above the lower platform.