"Slidejs autoplay not working" - How to fix it

The old code is

$('#slides').slidesjs({
width: 990,
height: 370,
navigation: false,
});

The new one is

$('#slides').slidesjs({
width: 990,
height: 370,
navigation: false,
play: {
active: false,
auto: true,
effect: "fade",
interval: 5000,
swap: true,
restartDelay: 2500,
},
effect: {
fade: {
speed: 600
}
}

});