Default [Q] Google Playstore error

I am using Sony Xperia M.
I use 2g cellular network of idea
The problem is

Whenever i open playstore it says google playstore needs to enable your background data.I tried force stop it and clearing data ,it then launches playstore like always.Whenever i download something,when it downloads 100-80 kb then it stops and says waiting for network.I tried using wifi,it works fine.But i want to know that can i download with cellular network.When my handset was new it worked fine.