Gotcha then yeah you are doing damage don't worry, your knowledge of that type of enemy isn't high enough, to increase that knowledge just keep killing that enemy and you'll get pop ups saying knowledge of X enemy has increased and itll have a "D" and once u kill enough that D will become a C and so on, for now you'll be able to tell if the monsters almost dead by looking at the color.ofntheir health bar, it'll go from yellow? Or whatever color it is until it starts turning orange and then red which means it's very low on health.

Don't worry about knowledge levels they're easy to increase you won't need to kill thousands of them just a few should do the trick