Won't pick up scroll event

[ljmerza]

I've written the code below but the scroll event doesn't pickup any scrolling. If I change the event to 'load' then it works just fine but I need it to work for scrolling. I'm on Chrome 51.0.2704.106 m (64-bit) for Windows 10 x64

var scrollax = new Scrollax(document.getElementById('posX'), {
    offset: 0
})

scrollax.on('scroll', function () {
    $(this.frame).css('transform', 'translateX(100%)')
})

scrollax.init()