There are different keys in NWN, one for the main program and one for each Expansion. You have to enter the key for Hordes of the Underdark. Alternative (if getting confused by the key entering dialogue), you can the keys by hand in the
nwncdkey.ini file. It should look like this:
Code:
;These are your CD Keys for Neverwinter Nights.
;DO NOT share these CD Keys with ANYONE.
;Apart from this installation, or when registering with the Official Neverwinter Nights Community Site [http://nwn.bioware.com],
; BioWare and Atari will NEVER ask you for this CD Key.
[CDKEY]
Key1=<Original NWN Key>
Key2=<Shadows of Undrentide Key>
Key3=<Hordes of the Underdark Key>
If you do not own one of the extensions, remove the corresponding line.
If you lost one of the keys (for example, in USA there was at least one bad shipping of SoU in which the key were printed on a tiny peace of paper that was lost very easily), contact ATARI.