Error by LevelModifiers

I find a error when i use LevelModifiers:
i set the mob-level is 32,base damge is 5,LevelModifiers damage is 1.6.
It shold be 56.2(1.6*32+5)
but...
The mob finally damage its 77.
I dont know how to explain it.
I can only think of this as a bug
sorry for my english