I've come up against this problem a couple times. the issue seems to be the whether the radius of the lockring tool is compatible with the diameter of a given lockring, and there is a lot of variation out there. The Park HCW-12 is radiused a little too large for a DA lockring, hence it slips. The Paul lockring tool is beautiful, but has a narrow diameter and won't fit (for example) Miche lockrings. Dunno if it fits DAs. The Hozan tool supposedly works because it is radiused kinda like a French Curve and therefore gets a better bite on a range of diameters. There are a lot of other lockring tools out there and it is trial-and-error to find one thats a fit. I got walked through this once by a curmudgeonly LBS owner who then offered to order a Hozan for me at a crazy price. I declined, and have been to lazy to get one from the internet.