Hello!
Have you met all the requirements to trigger the event?
Another requirement for the new desire is, to have finished at least the 6th quest ("Mysterious Virus", the quest to recruit Xora), I probably should have said that as well, my bad!
Incoming Spoilers:
Furthermore, it's not the very first room on the 4th floor that you have to enter, it is the very left one in the middle row!