Having problems with liquid layout

Fairly new to this sort of thing. I am making a page where the background needs to scale to the browser. Background is a mc. Here is the code:

Stage.scaleMode = “noScale”;
Stage.align = “C”;

sizeListener = new Object();
sizeListener.onResize = function() {
background._x = Stage.width/2
background._y = Stage.height/2
background._width = Stage.width * .9
background._height = Stage.height * .9


Now what i’ve noticed is that when it first loads into the browser it does not scale. When I manipulate the browser by pulling up on the bottom of the browser the background distorts and the top of the background is hidden. When I slide the left side of the browser to the right the background again becomes distorted and slightly hidden on the right edge of the browser.

Any clue what I’m doing wrong?

By the way it seems like it ignores the actionscript when it first loads. Then when I first try and do a resize it follows the above actionscript once . Then it ignores it for any future resizes.