disguise uniform help or bug

[lucwc]

Hi,
I am playing this game and find it is pretty fun to playing with. Now I am in level 3 but got issue: I can't change the uniform of warden! Under the action menu there is no 'change cloth' after I sucessfully enter the show room where warden is. I managed to kill warden and a guards. But found no way to get item 'change cloth'. I have changed cloth once when I enter the castle. I think that is necessary for quietly entering the prison. Does this is bug or I did somethng wrong? Really need help here!
Thanks