Not able to besiege castle despite negative relations

[rakarth]

Hey. So I'm currently a vassal of Ravenstern, and I decided I wanted to take a castle owned by Sarleon, even though we're not at war with them. I started attacking their lords and got my relation all the way down to -50, and yet the game will simply not let me besiege their castles. What's going on? Is this a Pendor thing? Pretty sure it was easy to do in Warband. Thanks.

 

[MitchyMatt]

Because you are a vassal of a kingdom that is not at war with another. They just hate you specifically. Because taking it would mean that Ravenstern gets the castle when they aren't even at war with Sarleon.