VerifyError: Error #1014: 无法找到类 mx.containers::Panel

1、错误描述

VerifyError: Error #1014: 无法找到类 mx.containers::Panel。

	at flash.display::MovieClip/nextFrame()
	at mx.managers::SystemManager/deferredNextFrame()[E:dev4.yframeworksprojectsframeworksrcmxmanagersSystemManager.as:278]
	at mx.managers::SystemManager/preloader_preloaderDocFrameReadyHandler()[E:dev4.yframeworksprojectsframeworksrcmxmanagersSystemManager.as:2627]
	at flash.events::EventDispatcher/dispatchEventFunction()
	at flash.events::EventDispatcher/dispatchEvent()
	at mx.preloaders::Preloader/timerHandler()[E:dev4.yframeworksprojectsframeworksrcmxpreloadersPreloader.as:515]
	at flash.utils::Timer/_timerDispatch()
	at flash.utils::Timer/tick()

2、错误原因

3、解决办法