This seems to simple to be your solution, but you said you attached the scale and drew to your full draw. Is that in reference to your hand reaching your anchor point, because if so the bowstring would be sitting a few inches forward of that-however tall your scale is. That would give a reduced weight. If you talk about full draw in the sense that the arrow was pulled back as far as your arrows would be at full draw-which is how you need to measure this-realize it can be hard (for me at least) to get the draw length quite right. Finally, at true full draw can you see the scale dial or do you have to let down some to read it?