Mine

mcCheck.onRollOver = function()
{						 
	showToolTip('Error Check');
}

mcCheck.onRollOut = function()
{						 
	hideToolTip(tooltip);
}

function showToolTip(aText:String)
{
	var tmp:MovieClip = attachMovie('tooltip','tooltip',_root.getNextHighestDepth(),{_alpha:0});
	var par = new mx.transitions.Tween(tmp, "_alpha", mx.transitions.easing.Strong.easeOut, tmp._alpha, 100, 1, true);
	//tmp.removeMovieClip();
	trace(tmp);
	tmp.txt.text = aText;
	tmp.onEnterFrame = function()
	{
		this._x = _root._xmouse - this._width;
		this._y = _root._ymouse - 10;
	}
}
function hideToolTip(target:MovieClip)
{
	trace(target);
	//pad = new mx.transitions.Tween(target, "_alpha", mx.transitions.easing.Strong.easeOut, target._alpha, 0, 1, true);
	target.removeMovieClip();
	//delete target;
}