Rocket Girl Tristana Skin Invalid?

Hello Fellow Summoners, I recently found out that Tristana was a very good AD carry so I began to play her. I quickly fell in love and purchased a skin from the Rito Ingame Store. I went to the good old fashion team builder just because I wanted to play Tristana right away, but then I got the message. "INVALID_SKIN". I am quite sad because now I can't play any games with my new skin I just spent $10 on. If someone has advice it is appreciated and please try to get Rito to see this post. Thanks -AnticShroom

Edit: Apparently this is only in Team Builder but I would still love help.