I just put on a new fiber optic sight on a new bow and now I'm having trouble getting the left/right to come out the same on all three pins. I've done the walkback tuning using one pin at 10, 15, and 20 yards and everything lines up. My problem is when shooting at 20 yards (middle pin) the grouping is about three inches off from my 10 yard pin. The 30 yard pin's grouping is closer to center (about 1-2 inches) , but the 10 yard pin is dead on. I'm confused about why the other pins aren't shooting with the 10 yard pin after doing the walkback. The only individual pin adjustment is elevation. Since I'm still a newby, any help is greatly appreciated.