Alpha property not working on TextField when publish for Reader 9

Hi,

I have a movie that is working fine when I publish for Reader 10, but when I publish for Reader 9, the code that assigns an alpha property to my TextFields stops working. I have a previous movie, which I probably did in CS4, that uses similar code to fade in and out TextFields. It was published for Reader 9 and works fine.Is it possible that something has changed in CS5 (note, I'm not using TLF text boxes, only dynamic TextFields)?

Here's an example of the code I'm using:

stop();
import fl.transitions.Tween;
import fl.transitions.TweenEvent;
import fl.transitions.easing.*;
import flash.events.*;
import flash.text.*;
import flash.text.TextFormat;
import flash.utils.Timer;
import flash.display.MovieClip;
import flash.display.Sprite;

var txtFormat1:TextFormat = new TextFormat();
txtFormat1.font = "Optima";
txtFormat1.color = 0x000000;
txtFormat1.bold = false;
txtFormat1.size = 16;
txtFormat1.leading = 2;

var subtitle:TextField = new TextField();
subtitle.autoSize = TextFieldAutoSize.CENTER;
subtitle.selectable = false;
subtitle.defaultTextFormat = txtFormat1;

var fadeInSubtitle:Tween;

addChild(subtitle);
subtitle.x = stage.stageWidth / 2 - subtitle.width / 2;
subtitle.y = stage.stageHeight / 2 - subtitle.height / 2;
subtitle.alpha = 0;
subtitle.text = "What is the most important question in";

fadeInSubtitle = new Tween(subtitle,"alpha",None.easeNone,0,1,3,true);