Check to be sure as per Rutty's instruction that the sight is actually moving, look through the front of the sight and take it side to side, you will see it move across the block, its obvious, and the range should be more than enough to take up the acceptable differences, and they should be shooting centre with the peep hole not that far away from centre visualy.
Also check that the windage knob grubscrew is tight, you may just be rotating the knob and not moving the sight.
Then check the front barrel weight/tube that the fore sight is mounted on is correctly located and secured correctly to the barrel, i.e upright not turned, they are only held by grub screws and if loose can turn.
Not sure what your model is but I presume it has the cantilever risers, if so, they can be different front to back which will upset the elevation range, and it is difficult but just possible to slightly misalign them side to side which will mess up the windage but I doubt enough to run out of sight adjustment. To be safe its best to have both the risers either fully up or fully down.
It does not take much to change shot centre but there should be masses of range in the sight to correct it.
Good Luck!
Robin
Walther KK500 Alutec expert special - Barnard .223 "wilde" in a Walther KK500 Alutec stock, mmm...tasty!! - Keppeler 6 mmBR with Walther grip and wood! I may be a Walther-phile?