fadein/out slow doesn't have the "slow" effect

The below code should fade in and out. What am I doing wrong?

$(window).scroll(function(){
    if ($(window).scrollTop() > 910){
        $('#logopiano').stop(true, true).fadeIn("slow", function() {
            $(this).show().css({ visibility: "visible" });
        });
    } else {
        $('#logopiano').stop(true, true).fadeOut("slow", function() {
            $(this).show().css({ visibility: "hidden" });
        });
    }
});

Here's the page: http://ift.tt/1zywkii