Well the Destiny Knot passes down five IV's from both parents to the child in Pokémon X and Y, but the IV's passed down are random so you're not guaranteed to get the IV's you want in the particular Stats you want.
So my advice would be to just keep trying and eventually you should get the Pokémon you want with the right Nature and IV's in the Stats you want.
>From Pokémon X and Y onward, if at least one parent holds a Destiny Knot, the baby will inherit five IVs instead of three.
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