First, the context: this is the second time I play the game, I still have original box and first played it about 10 years ago on Windows 2000; current replaying on a Windows 7 64 bits laptop with patch 1.21 and Arx Libertatis (it would not start on my system without it).

I want to play this time around in 'nice guy' mode, trying to solve everything the peaceful way if that is possible.

So, I got got the code, opened the secret passage, and sent the king on an extended toilet vacation.

I tried to talk to both the guard near the treasure room and the guard blocking access to the reservation room (blocking entrance to room 31 on this map: http://christiansarda.free.fr/anc_jeux/arx_niv3.html )
I showed both all 3 quest text messages ( the one about the king's allergy to wine, the one with the code, and the one about the death threat), then talked to them until theit reaction became invariant, then went back to the king.
The king does not react to any of those 3 either, nor does he instruct the guard to let me access the room, which he is supposed to do; I basically need to know precisely which paper need to be shown to which guard and which paper to the king, for him to unlock the situation.

I have penty of saves to older stages in the game, but I would like to be 100% sure that I hit a bug and did what I should have, before backtracking to an earlier save and restart this area.