I'm trying to raise one of my boker knives to whittling sharp but am having difficulty doing it (the blade is of 440c). I can raise a burr very easily with my 800grit on both sides and use 30 strokes on each side to get a noticable burr. Then when I jump to the 2000grit I can raise a burr on both sides but it's not as noticeable as it was with the 800grit and I use about 20 strokes on each side. Then I jump to the 6000grit and can't seem to raise a burr at all. I'm thinking I might be applying to much pressure at this level. What could be causing this to happen?