Alpha - Newbie question

Hi all

I’ve got an issue there, since I’ve started using flash one day ago only, I already have a problem with a simple feature…

I’d like to make a text transparent so I can create a little animation (frame 1 text is “invisble” frame 20 it’s “visible”)

So i used the ALPHA setting on it, o% at frame 1 and 100% at frame 20

But when I preview the animation, nothing happens, the text is visible the whole time :hangover:

I created a simple form and did the same, it worked…
Do I have to convert my text into something different than a Symbol ?

Thanks for your help !