Ok i've killed both the Sorcerer King's lieutenants and have both their keys, but still can't open the gates of the Sorcerer King's fortress to attack him. What is the reason for this please and how do you fix it? Happened in a previous game but somehow eventually started working. Tried re-trying and reloading and exiting and restarting the game over and over again in this game though, but still doesn't work.