I didn't let me load my world from beta , 14.5 ,which is on a previos update.

After opting out of Beta, 2 of worlds wouldn't load. The screen it gave me said,'' The world you're trying to play on is saved on a different update'' or someting. Also, it wouldn't let me copy those world, as well. So Mojang, I don't mean to sound rude-I love your game, but please fix this bug.