Extending a movieclip and calling a nested movieclip

1

Hi, I’m trying to do somthing like this:

[COLOR=Navy]class Timer extends MovieClip
{
// constructor
function Timer()
{
[/COLOR][COLOR=Navy]this.onEnterFrame = CountDown;
}

[/COLOR][COLOR=Navy] // CountDown
[/COLOR][COLOR=Navy] function CountDown ()
[/COLOR][COLOR=Navy] {
[/COLOR][COLOR=Navy] this.mask_mc._yscale–;
[/COLOR][COLOR=Navy]}
}[/COLOR]

And it won’t let me (There is no property with the name ‘mask_mc’.)…

Alternatively, I try to do this:
[COLOR=Navy]
class Timer
{
[/COLOR][COLOR=Navy] var __timer_mc:MovieClip;

[/COLOR][COLOR=Navy] // constructor
[/COLOR][COLOR=Navy]function Timer(timer_mc)
[/COLOR][COLOR=Navy] {
[/COLOR][COLOR=Navy] __timer_mc = timer_mc;
[/COLOR][COLOR=Navy] this.__timer_mc.onEnterFrame = CountDown;
[/COLOR][COLOR=Navy] }

[/COLOR][COLOR=Navy] // CountDown
[/COLOR][COLOR=Navy] function CountDown ()
[/COLOR][COLOR=Navy] {
[/COLOR][COLOR=Navy] this.mask_mc._yscale–;
[/COLOR][COLOR=Navy] }
}[/COLOR]

And it won’t work either…

So my question is:
How can I call a nested MovieClip from inside an onEnterFrame method (which is declared in a class that extends a MovieClip)?

Thnx,
EZ