You have made your body tag position:fixed and overflow:hidden, which means the scroll event is never triggered on the window, instead the scroll event is on #treats-for-trash. Waypoint listens to the scroll event on the window.
You should either change you css so that the window is scrolled instead of the article, or change the context of Waypoint to the right element, i.e. #treats-for-trash (see: http://imakewebthings.com/jquery-waypoints/#doc-options).