NBT tags don't register on item

Hey so I coded a constructor class to make special items and I added a method to add a NBT tag to the item but it's not working at all for some reason and I can't figure out why, here's the code(Note: the modifiers list is defined somewhere else but I tried defining it in the method and have a mention of it only in the method but it still doesn't work)

Code:

    public void addNBTTag(String name, double amount, String slot) {
        net.minecraft.server.v1_7_R4.ItemStack nmsStack = CraftItemStack.asNMSCopy(this.item);
        NBTTagCompound compound = (nmsStack.hasTag()) ? nmsStack.getTag() : new NBTTagCompound();
        if (name == "Unbreakable")
            compound.set("Unbreakable", new NBTTagByte((byte) 1));
        else {
            plugin.getServer().broadcastMessage("TEST");//It get here and broadcasts TEST
            NBTTagCompound attribute = new NBTTagCompound();
            attribute.set("AttributeName", new NBTTagString(name)); //Examples: "generic.attribute", "generic.maxHealth", "generic.movementSpeed", "generic.armor", "generic.followRange", "generic.knockbackResistance".
            attribute.set("Name", new NBTTagString(name));
            attribute.set("Amount", new NBTTagDouble(amount));
            attribute.set("Operation", new NBTTagInt(0));
            attribute.set("UUIDLeast", new NBTTagInt(894654));
            attribute.set("UUIDMost", new NBTTagInt(2872));
            if (slot != null)
                attribute.set("Slot", new NBTTagString(slot));
            modifiers.add(attribute);
            compound.set("AttributeModifiers", modifiers);
        }
        nmsStack.setTag(compound);
        this.item = CraftItemStack.asBukkitCopy(nmsStack);
    }

Can someone tell me what's the problem? Thanks in advance.

 

Do you get any error message in the console?

 

No