Never had this issue on multiple android devices. You probably did this already but just in case - Under "Sound and Notification" in settings, there is an uption for "When device is locked", verify that this is set to "on". Also under whatsapp settings itself there are settings for notification. You can verify those as well.
Originally Posted by
Jimmie76
Sadly that's already been allowed but thanks for the suggestion. It's frustrating because BBM didn't suffer from this and also gave you a time the message was read. However all of the people I used to message on there moved over to Whatsapp hence why I had to.