Forum:NPC doesn´t want to speak

Hello, I´ve got a problem with a npc (Thomas Hildern). I have the Quest to send him a bill from the Caravan´s Company but I´m not able to talk with him. He only say´s something like: "What do you need... " I have this problem since I complete his quest with the vault. Is there an option to reset this npc´s dialog? Sorry for my bad english. thx Dizzle