Hi there, author here. It was more than due to a 32-bit game running on 64-bit Windows and compatability mode didn't work. Ubisoft changed the reg key of the b

Hi there, author here. It was more than due to a 32-bit game running on 64-bit Windows and compatability mode didn't work. Ubisoft changed the reg key of the base game from it's retail key to "Uplay Install 87" and the expansion had no idea to look for that key at all. If you used the Ubisoft copy of both games, the expansion pack would never have found the base game.