Is code chicken core installed and if so try reinstaling it.
This depends a lot on how you server host has set up the server interface. If you can chose a stoneblock modpack do that. If not set it to the correct forge version and you should be able to run it.
Also could you tell us which host you are using that way we can help you a bit better.
And I hope you did read this: Choose the world type "voidworld" on servers. If something regarding quests or quests rewards are mentioned in the update log, do "/bq_admin default load" and "/bqs_loot default load" to update your questbook.