ACS Saying InvalidRegistration on Test Pushes to Android Devices

We are using ACS for push notifications, and have it working fine now on iOS.

For Android, we have a number of device tokens in the Subscribed Devices section.

When we do a test push, this is what we get for each Android device:

Updated at  2013-09-13T15:20:01+0000
Message Id  [mid]
Send Status     Fail
Message Status  Unknown
Channel     Web Console
Device Token    [dtoken]
Device Type     Android
Error Message   InvalidRegistration

Thanks for any assistance!