ActionScript 3.0 :: How To Load Movie And Goto Frame Inside It

I am starting to use as3 and I'm with problems. What I wanted to do is: I have a movieclip and I want to load another movie clip inside the main one. That part I can do and I use this code:

Code:
var carregador:Loader = new Loader();
var arquivo tring = "main.swf";
var requisicao:URLRequest = new URLRequest(arquivo);
carregador.x = 150;
carregador.y = 150;
carregador.load(requisicao);
this.addChild(carregador);

Now I want to have a button on the main movieclip with an action to send the loaded movie clip (main.swf) to frame 50. How can I do that?

I tried:
Code:
myBtn1.addEventListener(MouseEvent.MOUSE_UP, qualquer, false, 0, true);
function qualquer(MouseEvent) {
MovieClip(root).carregador.gotoAndStop(50);
}