Whats app push notification error, tried all possible ways. but problem was not solved

[susman vishnu]

hi. i'm using windows lumia 925. while using whats app i'm getting notification like "There's an issue with your phone that prevents you from receiving notifications for new messages" and also i rebooted my phone. Again the same problem i was getting. i don't know what to do right now. i prefer to use wifi from past 15 days. before that i used mobile data. i did'nt get any problem while i'm using mobile data.i even checked my mobile data settings while using wifi. it was disabled only. could you please suggest me what i have to do to rectify these error.