I think alot of things could play into this. What kind of angle was the shot? Quartering to/from? Broadside? High angle (from 15-20 feet in tree stand)? Was it a pass through? Was the arrow recovered?
How did the deer react after the shot? What kind of blood was on the scene of the hit? Any hair at the scene? If so what kind? Any water nearby? How long did you wait before following the trail?
Did the animal ever bed down before you lost the deer? Did it sound like the arrow hit the shoulder/bone?