Two things. First - is our scope one perfectly straight? If the crosshairs aren't perfectly vertical/horizontal it can cause problems. Then, are you sure you are keeping the limbs perfectly horizontal. That can cause left/right variance. The shooting high can be that the second pin isn't actually right for your arrow/tip/speed combination. I have also seen a scope that had so much paralex that if you didn't place your head exactly the same place on the stock each time it could cause problems. All problems will magnify the farther out you shoot.