My son is scared of his costume, should I just not take him out?

He is Whinnie the Pooh, he liked it at the store but when we got him home, I tryed it on him and he FREAKED screaming and kicked and kept saying "Scary" So I stopped trying to get it on him. What should I do, he never screams when I get him dressed. He doesnt like it. I can't take it back because it's one of the last ones in the store. He's been really showing fears to some weird things lately. I really want to take him out. Should I just wait and try again next year when he's more able to understand? What should I do?