Why did my monster had a stronger power but lost against a weaker monster. (DM2, 3, 4, 7, 8)

In DM2, 3, 4, 7, 8, there is a feature called alignment. Each alignment has a specific alignment that they are stronger or weaker against. All monster is assigned to a specific feature and if the monster's alignment is stronger than the opponent's monster, that monster will defeat the opponent's monster disregarding the Attack Power.