I usually reserve comment on situations like this primarly because I feel there are alot more guys out there with a bit more experience than myself. But I shot a buck a couple weeks ago that when I shot I thought it was pretty shot placement. As it turned out the shot was in fact a bit low and back. The arrow took out his liver and stomach and at first there was a decent blood trail that after 100 to 150 yds petered to virtually nothing. I tracked that night for a couple hours then backed off untill the next morning, I found him no farther than 75 yards from where I last seen him the night before. The point I'm trying to make is that, if you think it was a low shot, possibly the stomach was hit which could be the cause of the lost blood trail (stomach matter plugging the exit or entry wound). If you got a pass thru on the shot with blood up to the fletching you've got a dead deer somewhere more than likely. GOOD LUCK