Hexxit Gear, Changing Armor effects

[Stony]

Hello!

I have a Hexxit Server on version 1.5.2 (Hexxit version 1.0.10)

I changed some code at : .../mods/HexxitGear-1.0-23.jar/core/buff/BuffThiefSet.java

I added:        player.addPotionEffect(new PotionEffect(Potion.fireResistance.id, 20, 1));
        player.addPotionEffect(new PotionEffect(Potion.resistance.id, 20, 0));

to make the Thief armor stronger. I don't know why but the changes do not work when I join my Server.

Can Somebody help me? 

~Stony