FCS3 exported MC class communicate with as3 class

programming flash
1

i have a MovieClip that i add to stage within flashcs3 and have it linked to a predefined class, i want said movieclip to get a reffrence to my main program so it can communicate with a custom function of mine. what is the best method of doing something like this?

ive tried making an operator class, that would hold the var im trying to get, and naming it and adding it to stage but no luck

oper = MrOperator(stage.getChildByName("MrOperator"));
			if(oper==null){
				trace("null");
			}else{
				trace("not null");
				master = oper.master;
				master.passParticle(circleCollider);
				
				ready = true;
			}

but no luck it tells me i cant acces property of null object reffrence. any ideas?