I had this exact same problem the first time. I kept clicking on a black area trying to walk there which I think ended up being the ceiling or an archway or something. If I remember right you have to click more towards the bottom of the screen instead of straight ahead. trying clicking pretty close to your party too. as they get closer to the room you will be able to see into the room and just click in there to get them to walk in. You are on a staircase but unfortunatly you just can't see enough of the staircase to be able to tell whats going on
