Thumbnail slide fails to move when Brightness function is added?!

Hi
I have a thumbnail slide thats pretty basic. When I try to add this function to it the slide doesnt start moving when I move the mouse over:

function brighten(t, b, s) {

	t.onEnterFrame = function() {

		new Color(t).setTransform({rb:t.b, bb:t.b, gb:t.b});

		Math.round(t.b) == b ? delete t.onEnterFrame : (t.b == undefined ? t.b=0 : t.b += Math.ceil((b-t.b)*s));

	};

}

this.mc.onRollOver = function() {

	brighten(this, 200, .1);

	this.onRollOut = function() {

		brighten(this, 0, .1);

	};

};

Here is my .fla file: http://enelesfilm.se/ovrigt/forum/scroll.zip
With the above function in place it looks nice as the movieclip changes brightness but then the slide wont move when I move my mouse over.
How do I fix this?
Thanks for your help!