Reusable Tween Class?

[juncarlo]

I am wondering why this doesn't work?

function RollOver(object) {
scale_x = new mx.transitions.Tween(object, "_xscale", easeType, begin, end, duration, true);
scale_y = new mx.transitions.Tween(object, "_yscale", easeType, begin, end, duration, true);
}

Instance.onRollOver = function() {
RollOver(Instance);
}

I am planning to set a tween class for every button in my site, and I do not like to declare a tween class for each button. However, this approach doesn't seem to work. :(