I used to believe that hooey about a dull draw knife until I learned to control the tool and to use it more surgically. The "primitive" in primitive archery does not mean crude, inept, violent, or incautious. I have had far better luck with a draw knife that is wickedly sharp, take smaller bites and more of them, and control where the cutting edge is riding.
Others have also noted that your stave may be a little damp, too. I find no matter how careful I am with a damp stave, I will get grain tear out while chasing a ring. Put a light coat of oil on the ring you are at now, and put it somewhere warm where there is air movement. And if at all possible, put it on a kitchen scale, weigh it to the nearest gram, and write that weight on one end of the stave in pencil. Give it a week and see if the weight stayed the same.