scrollify disable scrolling up

Question

I try to disable scrolling up with scrollify, i try to use this snippet but its not working

$(window).scroll(function () {
  var iCurScrollPos = $(this).scrollTop();
  if (iCurScrollPos > iScrollPos) {
    if($.scrollify.isDisabled()) {
   $.scrollify.enable()

    }
    console.log('down')
  } else {
    console.log('up');
   $.scrollify.disable()

  }
    iScrollPos = iCurScrollPos;
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>