Issue: Nested sprites not visible

I have tried to create nested Sprite objects. But I see only the bigger square. What am I doing wrong?

var square:Sprite = new Sprite();
square.graphics.beginFill(0xFFCC00);
square.graphics.drawRect(0, 0, 100, 100);
square.x = 100;
square.y = 200;
var square1:Sprite = new Sprite();
square1.graphics.beginFill(0xFFCCFF);
square1.graphics.drawRect(0, 0, 50, 50);
square1.x = 100;
square1.y = 200;

addChild(square);
square.addChild(square1);