Thank you, You need another type of monster for them
Oh, is that what it is? I got both "m. press 2" and "behind" rooms and was confused when my goblins and hobgoblins wouldn't approach them! I'll keep that in mind, thank you for the reply!
Perhaps there could be some kind of indication in game of this? I'm not sure how you could do so with the simple yet elegant UI the game has, though. Only thing I could think of is something in the guide that mentions this, something like "if you find that your goblins can't utilize certain equipment of big cells, then perhaps someday another you'll find another type of that unit can..." (Though, maybe I should have guessed that's the case since only hobgoblins can use the transfer cells.)