Problem with moving starship.

function setupT2DScene()
{
	// Create fxSceneGraph2D.
	new fxSceneGraph2D(t2dSceneGraph);
	
	// Associate Scenegraph with Window.
	sceneWindow2D.setSceneGraph( t2dSceneGraph );
	
	// Set Camera Position to be centered on (0,0) with
	// view width/height of (100/80).
	sceneWindow2D.setCurrentCameraPosition( "0 0 100 75" );

 //Player Control

   // Create a new action map.
        new ActionMap(playerMap);

   // Bind keys to actions.
        
        playerMap.bindCmd(keyboard, "w", "playerUp();", "playerUpStop();");
        playerMap.bindCmd(keyboard, "s", "playerDown();", "playerDownStop();");
        playerMap.bindCmd(keyboard, "a", "playerLeft();", "playerLeftStop();");
        playerMap.bindCmd(keyboard, "d", "playerRight();", "playerRightStop();");
        playerMap.bindCmd(keyboard, "space", "playerFire();", "");


   // Activate the action map.
       playerMap.push();


  //Controling player

     function playerUp()
    {
  // Set the player moving up.
      $player.setLinearVelocityY( -10 );
    }