there are two wall panals darker gray than all the other stones but you have to find them in order there is one if you turn directly left one you get out of talking to the lady and one in the upper right hand corner then you should wee the door open hope this helps
They are quite easy to spot, just look at the map, there you can see the two hitten room's, the button is just in front of them! (maybe this is a fix in 1.3).