Ok, I have done it
, started clearing every space from right from entrance to left. It seems i missed the room in the centre of the castle to the NE, though I am pretty sure I have been there. As You said when entered it showed me decription of the room (it said that it was empty) and later I have returned to entrance and was able to pass.
Thank You very much, just a good thing that I can continue to play and hoping to finish it this sunday. Very nice till now, my cleric was down at start and had real trouble finding the resting place but later all was good and haven't trouble finishing with 4 party members. Now need to level up after talk with Mr. Caldwell.
Well done, I really wish i know how to do things like this