Change Alpha value on Mouse Roll Over?

[Tr0]

I'm a total newb to flash, I am using ActionScript 3.0 and all I'm trying to do is when the mouse rolls over a button it changes the alpha value to 50%.


Here's the code I'm using:
function onRollovr(evt:MouseEvent):void {
this.alpha = 50;
}
img1_btn.addEventListener(MouseEvent.ROLL_OVER,onRollovr);


Besides using the this.alpha approach, I've also tried _alpha and alpha which doesn't work either.

Any suggestions?

 

[Tr0]

Nevermind I figured it out.

Here's the code incase anyone is interested:

var newbutton:Sprite = new Sprite();
addChild(img1_btn);
img1_btn.addEventListener(MouseEvent.MOUSE_OVER,doOver);
img1_btn.addEventListener(MouseEvent.MOUSE_OUT,doOut);
function doOver(event:MouseEvent)
{
event.target.alpha = 0.5;
}
function doOut(event:MouseEvent)
{
event.target.alpha = 1;
}