Sometimes it can be your surface under you mat is not perfectly smooth. Also on my big mat I have a place right in the middle where I use it most often & the blade wants to skip when it gets to that area. If I move to a different spot it does okay so I figure it must be the mat. As far as the sharpeners, I have only used the one you mentioned & I couldn't tell it really helped much. I saw a new one the other day that was about $30, maybe gingher, & at that price I would hope it would work but would only want to buy it somewhere that would take it back if it doesn't.