[AS3] Changing stage variables from within a movie clip

[craziumdude]

I'm brand new at as3, just switched from as2. I want to change variables on the main stage's code from within a movie clip.

Say for example, I want to change a variable called 'chair'

In AS2, this is how I would do it:

(on the main stage)

chair = 2;

(in the movie clip)

_root.chair = 1;

So in AS3 I have:
(stage)

var chair:Number = 2;

(movie clip)

_root.chair = 1;

But all I get is a 1119 error saying 'Access of possibly undefined property chair through a reference with static type flash.displayisplayObject.'

I tried googling this problem but I couldn't quite word it right. Help?