Not bad but not grinding

I had always sharpened my knife with the belt sander. After the good recessions I thought that would be a good and kitchen-friendly alternative. (Better than ever have to walk into the garage and chic enough for to remain in the kitchen.)
However, I am not particularly happy with the sharpening result. The knife is already significantly sharper but really sharp is another matter. Furthermore, I noticed that in some knives sharpen at right corners in the blade are "torn" even though I had tried to keep me right on the (meager) instructions.