Plz fix

Ok I had this game go bored of it so I re downloaded it after a bit of time. So I opened up the game to see there was new maps but every time I try to get it. It said that i cant download it please check ur internet but my internet is working fine so plz tell me what I need to do to fix it?

Snicker598 about SAS: Zombie Assault 3, v3.0