Items count doesn't change

MCreator 2022.1; Minecraft Forge 1.16.5

I need to change items and count of them in main hand but I can't change count. If I held 64 items, there will be 64 dirt blocks. If I held 1 item, it will leave 1 dirt.

if (entity instanceof LivingEntity) {
    ItemStack _setstack = new ItemStack(Blocks.DIRT);
    _setstack.setCount(10);
    ((LivingEntity) entity).setHeldItem(Hand.MAIN_HAND, _setstack);
}

How can I fix that?