[silin]

или определить ссылку на тектфилд (для 8-ки):

class Cards extends MovieClip {
	public var color:String;
	public var txt:String;
	public var power:Number;
	public var trump:Boolean;
	private var tf:TextField;
	function setup() {
		trace(txt);
		this.attachMovie(color+"mc", color+"mc"+power, this.getNextHighestDepth(), {_x:19, _y:32});
		tf=this.createTextField("value_txt", this.getNextHighestDepth(), -3, -3.8, 41.2, 55.3);
		tf.text = txt;
	}
}