Iphone wont download apps from iphone itself?

[C J]

When I go into the app store on my iphone itself it browses perfectly fine, so i know there's nothing wrong with my internet, however when i download an app from my iphone, the app appears on my home screen but constantly says waiting, then tells me it cant connect to itunes store. However this works on wifi but not on my mobile internet although i can browse everything perfectly fine on my mobile internet. Is anyone else having the same problem? or does anyone know how to solve this ? Thanks