sighting in with scope

   all right,useing my 3/2 hole drill &tap left side mount.  now ready to put scope on .  useing Millet rings,which are set all the way towards the center line of rifle.   scope is Simmons Aztec 2.5x10,which is set and adjusted to my eyes.  at the range,starting at 25yds,scoped is bottomed out on the horizontal adjustment to the left.  I am still 4 inches off center of target.  getting great groups but not where,I'm aiming.   so how can I correct this,so poa and poi are the same?  useing swiss G11 ammo and shooting off bench rest.  what am I doing wrong or missing in trying to set this scope?

thank you for your time.
emmie