AdMob广告单元ID启用需要多长时间？

大约4个小时前，我创建了一个新的广告单元ID，并开始在未发布的Android应用的发布版本中使用它。但是我得到的只是一个空白视图和以下logcat输出：

I created a new Ad unit ID around 4 hours ago and started using it in the release build of my unreleased Android app. But all I get is a blank view and the following logcat output:

W/Ads: Received error HTTP response code: 400
W/Ads: There was a problem getting an ad response. ErrorCode: 0
W/Ads: Failed to load ad: 0

自广告以来同一AdMob帐户中其他应用的单位ID可以正常工作-即使在有问题的应用中使用时-我能提供的最好解释是，新ID尚未激活或尚未正确传播。

Since the the Ad unit IDs for the other apps in the same AdMob account work - even when used in the app in question - the best explanation I can come up with is that the new ID hasn't been activated or properly propagated yet.

这通常需要多长时间或我缺少什么？

How long does this usually take or what am I missing?