allied vassals dont join siege?

[matrond]

On mount and blade warband about 2 different allied vassals were with me when i was to attack a castle and when the siege begins there soliders arent in the battle.
Can someone please tell me how to fix this?

 

[Taimat396]

...You posted this in two sections :/

No idea if it'll work, but try talking to them and order 'em to siege the castle. Or try advice.