Mitch,
Run a perm marker along the edge of the blade. Use that to adjust the angle you are holding the knife as you run it along the Sharpmaker rods. You will be able to tell if you have the right angle when only the perm marker is removed. If it's not being removed, you are just running across the convexed bevel. Personally, if the knife is already sharp, I would start to maintain it on strops until it becomes necessary to actually sharpen it.