Import a swf made of UILoader to another fla's UILoader

Question

Sorry... I am new to AS 3, and my English is poor.
I made two flash.
First one I use it to import 5 images by UILoader,
and I made another one to import this flash,
and create 2 buttoms (play & stop) to control the imported flash.
But...the control.fla didn't work...
It seems that the img.swf didn't be imported.
PS: I choose to insert xml, and the "img.swf" in the table below was converted as img.swf
img.fla
var imgNum:int;
var imgNum0:int;
var targetX:int = 5;
ldr.x = -560;
stage.addEventListener(Event.ENTER_FRAME, changeImg);
function changeImg(e:Event):void
     if (ldr.x < -557)
          do
               imgNum0 = (Math.floor(Math.random()*4) + 1);
          while (imgNum0 == imgNum);
          imgNum = imgNum0;
          ldr.source = String("image" + imgNum + ".jpg");
          targetX = 5;
     else if (ldr.x > 0)
          targetX = -560;
     moveImg();
     function moveImg():void
          ldr.x += (targetX - ldr.x) / 10;
control.fla
//ldr.load(new URLRequest("img.swf"));
ldr.source = "img.swf";
play_btn.addEventListener(MouseEvent.CLICK,doPlay);
stop_btn.addEventListener(MouseEvent.CLICK,doStop);
function doPlay(e:MouseEvent):void
     MovieClip(ldr.content).play();
function doStop(e:MouseEvent):void
     MovieClip(ldr.content).stop();

Answer 1

When I want to move a movieclip from one fla to another I just right click it in the library and select copy.  Then I go to the library of the other fla, right click the library (off any other symbols) and select paste.