Animate same CSS property multiple times

It seems that animating the same property multiple times doesn't work.

$('#myItem')
    .scrollAnimate({
        startScroll: 0,
        endScroll: 300,
        cssProperty: 'top',
        before: 3500,
        after: 3400
    }).scrollAnimate({
        startScroll: 300,
        endScroll: 800,
        cssProperty: 'top',
        before: 3400,
        after: 3500
    })
