I am trying to sight in my new HK MP5SD6 .22 LR (the model made by Walther). I am having trouble getting the elevation adjusted correctly. It was shooting high, so the guide says to turn the dial clockwise to lower the point of impact. I turned it and turned it and my elevation didn't seem to change at all. It won't turn anymore and I am still two inches high. I am normally a very good shot with iron sights, so I can't figure out why it doesn't change. The windage was a snap.