Controling mcs on stage with a class (how?)

I have a main ButtonClassTest class that extends the MovieClip class. Then I have a ButtonTest9 class that extends this ButtonClassTest and a ButtonTest9.fla.

It works fine (click, rollover, etc) when I link a movieclip in the library of my ButtonTest9.fla to ButtonTest9 and place instances of this mc on stage (button1_mc and button2_mc). However, I’m not being able to control anything about the instances themselves, like, setting button1_mc.alpha = .5 in my ButtonTest9 class.

I tried a whole bunch of things, like [FONT=“Courier New”]Stage.[/FONT], [FONT=“Courier New”]this.[/FONT], putting it into functions, not linking the mc in the library and using [FONT=“Courier New”]new ButtonTest9[/FONT] instead… Each thing gives me a different error.

There must be a simple way to do this. Can anyone please, please help? Many thanks!