dtgreene: (You should mention which game you're talking about when posting a topic, preferably in the topic title; I am assuming you mean Bard's Tale 1.)
Do you have a levitation effect active? If you do not, then you can't take portals upward.
Alternatively, level 3 of the castle is not a no-teleport floor, so you could just APAR up there. (For whatever reason, APAR and PHDO won't work on level 2, but will on level 3.)
krunge: Thank you for the suggestion of APAR. Yes, BT1. I haven't used levitation. Was able to APAR. Tried the portal down in the sewers the hotkey worked fine. So the problem is limited to the Harkyn's Castle up portal.
You can go down portals without levitation; your party will just take some damage.
You can't go *up* portals without levitation.
So, if you want to go up a portal without just teleporting around it, cast a levitation spell first.
Does this make sense?
(The original manual, I believe, actually mentions this.)