IMO i thank that you might have got a gut shot or a intestant shot or you might have hit some meat. but if you did hit the deer a little far back dont get discouraged those shots can somtimes be lethal. the first deer that i killed with my boy was 22 yard and was just tiping along i shot her on the move and she fell right there( i hit her just infront of her hind quarter in the intestants) so i would go back and check the area good.