garageband skipping notes on playback

when i am trying to make songs on garageband i often find that it randomly skips notes on playback. and i mean this by that they randomly go silent and its always that specific note or im that specific sequence. i use the editor thing to manually put in the notes and i use garageband for ipad and iphone and ive encountered this problem on both. i dont know why this is happening and i havent found a way to fix it yet. can someone help me and please tell me whats going on? this is a terrible glitch and it is making me so angry. thanks