Mundo's Corperate Skin can not use in the game!

I have a very good Mundo's Corperate Skin, i get it from box random, however, in my champion list, It shows I owned it, but today when I play in Rank game, It shows I didn't own it, and I can't use. I'm so sad, and I lost that game. Would some guy help me to solve this question. The same situation also happens in ARAM and Blind pick model. It is a BUG!!!!!!