[jQuery] Problem with Interface > droppable > onhover

I have a problem with whis:
            $('#drag').Draggable();
            $('#holder .dropzone').Droppable({
                    accept :        'dropaccept',
                    activeclass:    'dropactive',
                    hoverclass:    'dropzonehover',
                    tolerance:    'pointer',
                    ondrop:    function (drag) {
         alert(this); //the
droppable
         alert(drag); //the
draggable
             },
                    onHover: function(drag) { alert(this); //the droppable }
            });
when I remove onhover line it works but if I add it it sops working,
and ideas?
it is driving me nuts...