[Solved]KnockbackResistance attribute not working on my ite

So, I've for few days been trying to make an item which would make the user immune to all sorts of knockback
Only way to do that seemed to be the knockback attribute on items, so I made this

KnockbackHelmet:
Id: 298
Display: '&3Test'
Attributes:
MainHand:
KnockbackResistance: 99%
Options:
Unbreakable: true

Turns out, it gives no resistance to knockback at all, and I've tried everything that I could think of, and no luck :/

What am I doing wrong?