Certain champs won't show up in champ select?!

SO... I was in a ranked game picking my champion (routine things, etc.) and when I decided I wanted to play Graves, I type him up in the search bar, but nothing had showed up... I had double checked my spelling, and still no icon for Graves came up, after that mess I tried fumbling around the scroll bar looking for him, and before I knew it, i had been kicked from the match and given a 30 minute wait punishment. Any ideas on how this happened?