Allocate Mana Blessing doesn't do anything on amulet?

I have allocate mana blessing on my amulet, which should give me extra 20 and 5% increase maximum mana, the amulet itself have 50 mana, and I have multiple passive nodes for maximum mana as well, but when I take the amulet off my mana only decrease from 3515 -> 3456, which is 59 mana decrease. This telling me the allocating stuff is not working or I'm understanding it wrong?

Edit: I understood the allocating things wrong, I already having the passive skill in the tree hence there is no difference...