Calling methods of a loaded Flex swf

Hi all!

I’m loading a swf made in pure Flex from a pure ActionScript project. The Flex swf implements an interface. I load that swf and then I try to call a method of the loaded Flex swf but it doesn’t work.

This is the Flex swf that I’m loading:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="" implements="IApp" layout="absolute">
            public function init():void
                trace( "INIT OK!!" );

This is the interface IApp:

    public interface IApp
        function init():void;

And this is how I load the Flex swf in the ActionScript pure project and try to call the init method:

package {

    import flash.display.Loader;
    import flash.display.MovieClip;
    import flash.display.Sprite;
    import flash.text.*;

    public class PruebaGS extends Sprite
        public var URL:String = new String( "FlexSWF.swf" );
        public var loader:Loader;
        public function PruebaGS()
               loader = new Loader();
               loader.contentLoaderInfo.addEventListener(Event.COMPLETE, completeHandler);
               loader.load( new URLRequest(URL));
        public function completeHandler( evt:Event ):void
            var movie:IApp = as IApp;

The problem is that is of type _FlexSWF_mx_managers_SystemManager so it cannot be converted to IApp.

Does anyone know what is the problem?