Difficulty sharpening a knife,?

I have a Buck 1 10 hunting knife that is very hard to sharpen.I have the very best hones and whet stones including diamond and 'india' stones,some water and some oil but this one knife is especially hard to sharpen.I own several ddifferent Buckknives and this is the only one I have trouble sharpening. Can anyone advise me on how to do it?