you are missing the following line in the BroadcastReceiver (manifest file)
Without this line, the device wasn’t registered successfully with backendless’ servers, but there were no errors!!
The following line didn’t throw any exception -
Backendless.Messaging.registerDevice(gcmSenderId, new AsyncCallback<Void>() {
Please add this line to the documentation and/or throw some informative error when the action is missing.