"The Challenge of Wulfstan" - "Brothers" [Campaign 2, Mission 4]

I replayed the mission from the beginning three times tonight, it's a complete dead end :smile32:
Duncan is not active; he stands at the road junction, and not only does he not react, but it's also impossible to pass by him to reach the castle :mad: :mad: :mad:
On the third try, I got the Astral Gate in "Mystery of the Dragons" and jumped over the villain, but the city is overrun, and the mission doesn't end :(.
Completed tasks (checkmarks are present): Wulfstan survived!!! (which should appear at the very end of the mission), the city was captured, the attack by Rolf was repelled.
Not completed (no checkmark): meet with Duncan.
Does anyone have any wise ideas???