That was the problem. I had to move my diplomat to the front of the party and then it allowed me to use bluff. However, now I have another problem. Bluffing the guards takes you directly to the dungeon bypassing the floor in between where Burne's apprentice is. Attempting to go back up to that floor just initiates the same options with the guards again which means you either go back to the dungeon or back to the ground floor. So, until I can scribe Scrolls of invisibility, which I can't right now because my wizard doesn't know the spell, there doesn't appear to be anything I can do. I think Burne's apprentice might sell that scroll , but I have no way of getting to her. My only option now is to try to find a scroll of invisibility somewhere else or wait until my next level up. This is a poorly designed section.