Can't connect to chat??

[Selvin Rajkumar Jennison R]

This is my 4th month with lumia 520, from last month on wards i am not able to use fb chat or see who's online in my mobile....:unhappy:any idea of why i am not able to view all of a sudden?? any solutions guys?
And also my whatsapp push message is not received. it shows some connectivity issue. I have rebooted the device several times, uninstalled it and again tried to install but the same issue shows up.

 

[luk3ja]

Possible causes...you have low battery or battery saver is permanently on, no internet connection, wifi is down, ran out of credit, ultra slow data connection