Same thing happened to me when I first got it a few days ago but it was my fault or maybe it came off by default...
when you pull down the tab from the top of the screen, at the top next to "Screen rotation" there is an option called "Mobile data", if it is not on then it will do this. Just make sure it is on. This should fix it.
If this doesn't fix it then this will for sure: go to Settings, then More settings, then Mobile networks and check the box next to Use packet data.... I did this at the same time.
Hope it fixes it for you guys, I wasn't going to go to the store or call for help unless really needed.