Flex / AS3: why I couldn't listen to the ready event of the module

code snippet follows

       var depTree:IModuleInfo=ModuleManager.getModule('modules/depTree.swf');
        if(!depTree.loaded){
            depTree.addEventListener(ModuleEvent.ERROR, onModuleError);
            depTree.addEventListener(ModuleEvent.PROGRESS,onModuleProgress);
            depTree.addEventListener(ModuleEvent.SETUP,onModuleSetup);
            depTree.addEventListener(ModuleEvent.READY,onDepTreeModuleReady);
            depTree.load();
        }

    private function onDepTreeModuleReady(event:ModuleEvent):void{
        logger.debug("depTree module was ready");
        var moduleInfo:IModuleInfo = event.currentTarget as IModuleInfo;
        Panel(component).addChild(moduleInfo.factory.create() as Module);
    }

      

        
        
        
      

    

when i run my application i got the message "[SWF] /depTree.swf - 336.967 bytes after decompression" so i am sure the depTree module has been loaded, also depTree.read is true. but the onDepTreeModuleReady function never seems to be called, I didn't have a debug message and the app interface hasn't changed.