User blog:ScreamKings/HELP!

Hello! I'm ScreamKings, and I'm the founder of Chanel Oberlin Wikia. I need help with the Special:AchievementsCustomize page of my Wikia. Everytime I put in "Picture" or "Pictures track" in the "Create new track in category", it says that "The specified category does not exist." . Can anybody help me?!