mc mask

Hey,

I created a scrollbar through code, and i have a main area that is masked by a clip i create. When the scrollbar moves, it blurs the content, but it looks like its blurring the mask as well.

my mask function is here:

maskClip.graphics.beginFill(0xFFFFFF);
maskClip.graphics.drawRect(0, 0, widthVar, heightVar);
maskClip.graphics.endFill();
maskClip.cacheAsBitmap = true;

main.mask = maskClip;

addChild(main);
addChild(maskClip);

and my blurring function is here:

blur.blurY = Math.abs(dy);
blur.blurX = 0;
blur.quality = BitmapFilterQuality.HIGH;
main.filters = [blur];

any ideas? Thanks!