No worries. Thank you for your attention. I figured it out. Just in case you wanna know:
Turns out, you will only get Orc Clue 4 if you carry a book with you, which can be obtained next to the skull, in the room where you release the poisonous gas. You need to get it before entering the room in B1. You MUST do this before THE FIRST TIME ENTERING, otherwise, Clue 4 is locked away forever.
I did that on my second attempt and it works.