无法在谷歌应用引擎中为php应用程序配置更改对象通知

当我尝试使用gsutil命令设置通知时，我得到以下错误:

gsutil notification watchbucket https://APPLICATION-ID.appspot.com/cron gs://bucket

Watching bucket gs://APPLICATION-ID.appspot.com/ with application URL https://APPLICATION-ID.appspot.com/cron ...
Watch bucket attempt failed:
  AccessDeniedException: 403 Forbidden
You attempted to watch a bucket with an application URL of:
  https://APPLICATION-ID.appspot.com/cron
which is not authorized for your project. Please ensure that you are using
Service Account authentication and that the Service Account's project is
authorized for the application URL. Notification endpoint URLs must also be
whitelisted in your Cloud Console project. To do that, the domain must also be
verified using Google Webmaster Tools. For instructions, please see:
  https://cloud.google.com/storage/docs/object-change-notification#_Authorization
AccessDeniedException: 403 Forbidden

我已经按照以下url中的所有步骤进行了通知授权:

https://cloud.google.com/storage/docs/object-change-notification

但我仍然得到上述错误。我错过了哪一步?

谢谢