jquery - Auto scroll does not work as desired

Question

I was looking at an example here

http://jsfiddle.net/davidThomas/bw6Xw/6/

div.on('mousemove', function(e) {
    var cPointY = e.pageY,
        dP = ((cPointY / wrapHeight));
    div.scrollTop((listHeight * dP) - wrapScreenHeight);

});

I tried to replicate the same here http://jsfiddle.net/bw6Xw/188/ but it does not work.

Any reasons why?