Alexa - 对AudioPlayer.PlaybackStarted的响应导致错误

Question

在我的Alexa技能中，我通过AudioPlayer指令播放MP3文件。

当文件开始播放时，我得到：

{
   "type": "AudioPlayer.PlaybackStarted",
   "requestId": "requestId",
   "timestamp": "2018-02-28T13:17:54Z",
   "locale": "en-US",
   "token": "tokenstring",
   "offsetInMilliseconds": 0
}

我的服务未生成对此事件的响应，但我立即收到此错误：

{
   "type": "System.ExceptionEncountered",
   "requestId": "requestId,
   "timestamp": "2018-02-28T13:17:55Z",
   "locale": "en-US",
   "error": {
      "type": "INVALID_RESPONSE",
      "message": "An exception occurred while dispatching the request to the skill."
   },
   "cause": {
      "requestId": "amzn1.echo-api.request.8492b40e-1698-409f-8bed-61dc1f3de663"
   }
}

在文件中它说我不必回应这个事件，但是我需要发送回Alexa的强制性内容吗？也许是HTTP状态？