Well, it happened a lot of times than a closed door can't be opened,even by a thief ; it says that the door's locked and is protected against simpliest magical spells...
What can i do to open it ?

Abother problem of the same type : in the cimetary area, in the underground temple, there's a locked door and it says that because of a high feeling of danger, my thief can't open the door, neither than an unlock spells...
So, how to enter anyway ?

This doors are specials/quest doors... and only in the right time you'll open it... http://www.tgeweb.com/ironworks/cgi-...iles/smile.gif

Whenever you get that message, the game trying to tell you that the door in question can be opened once you've done the right things. They are usually quest related, and you cannot open them until you've performed certain actions associated with a given quest.

You won't be able to open the door under the crypts until the end of Chapter 3.
http://www.tgeweb.com/ironworks/cgi-...es/biggrin.gif

Damn, that's frustrating... but anyway, i'll wait till the right time !
Thank you guys !