jQuery animation fade effect

Question

The fade effect here isn't working.... ui.fadebox is a white div tag that is supposed to fade in and fade out. It's not fading though, even when the time is set to 5000 it's just like setting the display from block/none. There's no transitioning...

            ui.fadeBox.animate({
                    opacity: 1
                },
                500,
                function () {
                    $('.active', ui.container).removeClass('active');

                    $(ui.banners[idx]).addClass('active');

                    ui.fadeBox.animate({
                        opacity: 1
                    },
                    500,
                    function () {
                        ui.fadeBox.css("display", "none");
                    });
            });