on(Rollover) {bring to front}

I have several buttons on the stage, but because they all overlap, I need which even one you mouseover to change it's depth so that it is on top.

I tried doing something like:

Code:

---

on (rollOver) {
        trace(_this.getDepth());
        _this.swapDepths(1);
}

---

... but it doesn't seem to have the required effect. And the trace outputs a figure like "-16375".

This code only works for movie clips........

frame script:

btn1.onRelease = function () {
this.swapDepths(this.getNextHighestDepth());
};
btn2.onRelease = function () {
this.swapDepths(this.getNextHighestDepth());
};
btn3.onRelease = function () {
this.swapDepths(this.getNextHighestDepth());
};
btn4.onRelease = function () {
this.swapDepths(this.getNextHighestDepth());
};

It has to be buttons, not movieclips.

Do buttons not support swapDepths() ??

Code:

---

var oldDepth:Number;

btn.onRollOver = function(){
        oldDepth = this.getDepth();
        this.swapDepths(_root.getNextHighestDepth());
}

btn.onRollOut = function(){
        this.swapDepths(oldDepth);
}

---