It sounds to me like something went wrong in the database update.
I would try runnning the database uninstaller for the mod, then let it reinstall itself.
Before you do that, you should backup your database.
Any anti-spam acp settings will be lost if you do this, so if there is anything you want to save (list of flagged users, spam words list, etc) let me know before you do this and I can tell you how to back that data up.
After you get a backup, if you don't mind losing those settings (or we back them up for you), run antispam/remove_asacp.php in your web browser. After running that, the mod should automatically be reinstalled on the board, so check the permissions again to see if they are working.
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