Development Flash ActionScript

package{
  import flash.display.Sprite;
  import flash.system.Capabilities;
  import flash.net.*;
  public class Main extends Sprite{
    public function Main(){
        var resX:int = flash.system.Capabilities.screenResolutionX;
        var resY:int = flash.system.Capabilities.screenResolutionY;
        
        if ( (resX <= 240) && (resY <= 320) ) {
          var url:String = "main_pocketPC.swf";
        }else {
          var url:String = "main_desktop.swf";
        }
        trace(new URLRequest(url));
    }
  }
}