[Q] whats app,hike and viber are not working in background topic

Whatsapp messages are not auto received. Messages will only come in upon manually opening the app. It goes for the same with the apps viber and hike messenges. I have only these three apps and I don't know about the remaining apps.I have checked all the setting like background restriction of data,checking the notification option in app settings, but the problem is not solved. Please help me!!!!!!!!!!!!!!!!