Dont work damage taken goes to mana

does not work correctly energy shield.
i have telekinesis 20/20+7
have belt tal rasha + 2 rune ith, energy shield without = 67%
I get damage from monsters, and mana is not deducted.

Is not working like this. The text is a bit missleading.
15% damage goes to mana means that you still get damaged as normal but after you took the damage and life goes lower your mana is + xx% of your damage taken.
so is not supossed to work as a mana shield and lose mana instead of life, but actually get some mana being hit.