Text alpha tweening

Hi!

I’m trying to make a tweening with text, for example a letter “a” that starts with alpha 100 and ends with alpha 0. On the stage I move the timeline and looks good. But when I publish it, it does no fx at all. Am I missing something?

Here I have an example with a letter and an image. The image does tween, but the letter doesn’t, and they have the exact same tween and alpha.
http://www.guidogarfunkel.com.ar/prueba.swf

Thanx!