My account banned for ninja looting

I was playing as my warrior char today and i did 4 or 5 dungeon in which 1 was random heroic and other are of my choice for specific item in dungeon i need the item that i need for all other i either pass it or some time greed roll it and when i was in stromwind near dummies trying out macros for pvp spec warrior a message came to me that i was banned for ninja looting in dungeon but i dont get it what i did wrong or anything that goes against rule if i did pls let me know.

sorry for writing it here first time this happens but now i know that your not supposed to write this here but use a ban appeal service pls ignore this thread