Problem with instantiated prefabs. Object stays dark

So I've download a grass pack from the assest store. I'm using the prefabs(grass') as an array, so I dragged and dropped them into the array section of the script. Everything works fine, it spawns as it should (like the coins and enemies using the same script) but when the grass instantiates its dark. it stays black even when a light is shined directly onto it. this isn't happen with the coins (also an array) or the enemies. I'm using unity 5.3