Laco Tweens problems [renamed]

programming flash
1

I have attached the code, and fla, dont really need to look at all the code, just wanted to post all of it for troubleshooting purposes. But Man i dont know about this " callback " function option in the Lacos tweening class, so can anyone tell me what type of ( if ) statements I need to have to tell flash to attach/loadMovie into a empty movieclip , once the content area has been revealed ( see FLA ) and then when another button is clicked to remove that attach movie/loaded movie clip ? plzzzzzzz guy

// edited 
#include "lmc_tween.as" 
// 
var down = this.onRelease;
var total = 6; 
var active = 0; 
for (var i = 1; i<=total; i++) 
{ 
   this["btn"+i].i = i; 
   this["btn"+i].startY = this["btn"+i]._y; 
   this["btn"+i].onRollOver = function():Void 
   { 
      if(active!=this.i) 
      { 
         this.colorTo(0x000000, 0.1, "easeOutSine"); 
         this.scaleTo(120, 1, "easeOutElastic"); 
      } 
   } 
    
   this["btn"+i].onRollOut = function():Void 
   { 
      if(active!=this.i) 
      { 
         this.colorTo(0xFF0000, 0.5, "easeOutSine"); 
         this.scaleTo(100, 1, "easeOutElastic"); 
      } 
   } 
    
   this["btn"+i].onRelease = function():Void 
   { 
      var temp = active; 
      active = this.i; 
      this._parent["btn"+temp].onRollOut(); 
      this.tween("_y", 400, 4, "easeOutElastic",0,mcLoad); 
        
      for(var i=1; i<=total; i++) 
      { 
        x = this._parent["btn"+(i)]._x 
         if(i<this.i) 
         { 
            y = this._parent["btn"+(i+1)].startY-260; 
         } 
         else if(i>this.i) 
         { 
            y = this._parent["btn"+(i-1)].startY+260; 
         } 
         else if(i==this.i) 
         { 
            y = this.startY; 
         } 
         this._parent["btn"+i].slideTo(x,y, 4, "easeOutElastic",0,mcLoad); 
      } 
   } 
} 
function mcLoad()
 {
 if(btn[1].onRelease==true){
  trace("This is progress, now load a movie here");
  this.loadMovie("ball.sws",this.getNextHighestDepth());
 }else if(btn[1].onRelease==false){
  trace("Dont load nothing please");
 }
}