what could be happening is that you're not leaving enough room at your in and out points. Between each shot, you need at least 10-20 seconds pre-roll at the beginning and end of each shot. What this means is that when you shoot, start shooting a good amount of time before your subject starts moving, and keep rolling after, don't just stop recording right away. This way, you will always be sure that you have enough room in between clips to set in and out points. If you start recording as soon as your subject starts their action and stop right after, you will not be able to capture the whole clip, you may end up being able to capture only half of it or the middle chunk of it. Hope this helps.