At this point, if you're already read the other article on push notifications and still not receiving push notifications, there may be an issue with your device. You can test push notifications using the "Push Notification Test" app from Google Play. This App let's you test Push Notifications via Google Cloud Messaging (https://developers.google.com/cloud-messaging/) on your device. Can be helpful if notifications are not working in an App on your device.
here is a link to the Push Notification testing app