Challenger 2 Black Knight Hard Kill System Isn't Working

Ive been playing the Challenger 2 Black Knight and the active protection system almost never works, me and my friend were testing Tow 2bs and he could hit me with the top attacks if he aimed them really high up and they would knock out my tank and earlier today I had a khrizantema shoot at me from across the map and my active protection system didn’t stop his missile

did the sensors on the turret cheeks have line of sight to the missile?

My turret was facing where the missile was, the khrizantema hit the side of my hull