Shield absorption question

Hi guys I have a question if someone can explain.
I am defending generator with 11d and inspector & shields are on 30.
Attacker sending 15d and its known he got a king.
I am left with 1d after combat.So why the shields did not absorbed the full DMG?
I am defending generator with 11d and inspector & shields are on 30.
Attacker sending 15d and its known he got a king.
I am left with 1d after combat.So why the shields did not absorbed the full DMG?