This might be a dumb question but are you sure you're adjusting the sight correctly? If you are shooting low, move the sight down, if you are shooting high move it up. In other words "chase your arrows" with the sight.

Other problems might be due to knocking point, rest position, etc...

Try to re-set up your bow making sure everything is positioned correctly. Also start out with making gang adjustments with the whole sight ring before moving individual pins.

Good luck.

Edit:Post a picture with an arrow nocked if you can, this may help us figure out what is wrong.