I have a problem where the zeroth index of my image array is failing to display (except for the first time). If you run the program, you can go forward normally and do all of the flips regularly, but then when you go backwards, there is a glitch. After displaying the second index, and then the first index, it will go to the zeroth index, but not display anything new, and then you can keep on going and the program will jump to the 22nd index and display that normally. If you try to go forward again, the index goes to 0, and is not displayed. The flips are also messed up when you are on imageIndex == 0.