The first frame is usually not considered a frame as no animation comes from it - but starts from it. So the second frame is actually the first frame of animati

The first frame is usually not considered a frame as no animation comes from it - but starts from it. So the second frame is actually the first frame of animation. So if you want 100 frames of animation - you need 101 frames. Therefore your first frame is really "0" and you start counting (moving) from there.