Polymer Firebase图片上传错误

Question

我的firebase app配置如此

<!-- NOT THE REAL VALUES --->
<firebase-app
  auth-domain="<auth domain>"
  database-url="https:DATABASE url"
  api-key="API KEY"
  storageBucket= "thebucket.appspot.com">
</firebase-app>

每次尝试上传图片时都会出现以下错误

"Firebase Storage: No default bucket found. Did you set the 'storageBucket' property when initializing the app?"

我不明白存储Bucket属性存在。