I faced the same problem, then found that it was caused by a system settings parameter related to Apps. If this problem occurs when you are downloading apps via mobile data, then follow the below procedure.
- go to System settings -> Data usage
- Here, you will find a tab with the name of your cell phone operator, for mobile 3G data.
- Turn mobile data ON
- Then uncheck the "Set mobile data limit" checkbox
Now you are good to go.
What happens is when the data limit is restricted/set, for some parameter/setting in the application, the OS wont allow to download apps from store.