ActionScript 3.0 :: Flash - Object Oriented Game Design Error?

ame_Manager.as= this manages the creation of balloons, players and collisionsBalloon.as= This is the balloon classPlayer.as=This is the player classThe Game Manager class will pass stage to the balloon and player classes and create them. I add these two in the Game Manager class.In the balloon class i add all the balloons in an balloon array.Now when i run the code i am unable to check for collisions as nothing happens when the player and balloon collides. and i get a child must be a caller of the display object when i ry to remove the balloons after they have crossed the stage.I have been trying to make it work for a long time a the game is very very simple.in the Object Oriented way of designing this simple game as i think that is where my error might be.I will post the code for these belowGame Manager.as

Code:
public class GameManager extends MovieClip{
public var backGround:BackGround;

[code].....