Getting hit by a rock is an instakill and the code seemed quite complicated. worked different than melee, missiles and fire. True, the mechanics of catapults, rocks etc. Tried turning inv mode and i instakill the caliph with a few horse archers its hilarious. troops will still die if they are hit by catapults, trebuchets and mangonel. If you have bought the game on steam, try updating or reinstalling as it should be version 1.41. If this is the case then it would make sense that my table is not working for you.
I used the CD-upgrade and afterwards installed the steam version, but that made both my versions 1.41. Steam has had another update afterwards bringing it to 1.41. Im playing the enhance edition steam the version says in the menu is 1.4 Hi shemy, have you upgraded the CD version? Because I think that is version 1.4.