Code:
import fl.transitions.*;
import fl.transitions.easing.*;
import flash.events.Event;

var myTween:Tween = new Tween(PopUp_mc,"y",Strong.easeOut,PopUp_mc.y,300,1,true);
var lastFrame:int = -1;
addEventListener(Event.ENTER_FRAME, upDate);

function upDate(e:Event):void {
        if (lastFrame != currentFrame) {
                lastFrame = currentFrame;
                trace("The frame has changed to " + currentFrame);
                if (currentFrame == 1 || currentFrame == 4) {
                        new Tween(PopUp_mc,"y",Strong.easeOut,PopUp_mc.y,300,1,true);
                } else {
                        new Tween(PopUp_mc,"y",Strong.easeOut,PopUp_mc.y,500,1,true);
                }
        }
}