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Hello JoelH50. It has been a few years since I have played around with the 15 puzzle. However, I am not sure I ever encountered a case with the 11 and 12 being in the wrong places if all the other tiles were in the correct locations. Are you playing on a computer or on a physical 15 Puzzle game? If you are playing on a physical 15 puzzle game it is possible that someone took some of the tiles out and switched their places. If that is the case it is likely that your puzzle is impossible to solve. The tiles in the game aren't allowed to be scrambled randomly to any position, so if some of the tiles have been physically removed and swapped locations the puzzle may be impossible to solve. You can find more info on 15 Puzzles on various websites including Wikipedia. Hope this helps.