Trigger Finger?

Hi guys,
I hope I can make sense out of this question, here goes. Where is the proper place for the trigger finger to contact the trigger? When I was in boot camp at P.I. we were shown a technique for finding the sweet spot on our trigger finger by placing a pencil in the area where the thumb meets the hand and the point of the pencil touching the index finger. When mimicking a trigger squeeze the pencil should travel straight toward the rear. If it does not, then the point of the pencil should be repositioned and the process repeated. When the pencil/pen traveled straight back, that area of the trigger finger was marked and that was were it should contact the trigger. My sweet spot is directly behind the first joint of the index finger. This method does not seem to work when firing my MKII. When looking at the "wheel of misfortune" on http://www.bullseyepistol.com/ my shots in the one handed position are a little high but mainly printing to the left. I don't have this problem when shooting off bags. Any reccomendations on trigger finger placement? Thanks,
L'man