Access denied for user ... to database

Hi,

on D6, I'm getting the following error when adding a faceted search environment (/admin/settings/faceted_search):

user warning: Access denied for user '{databaseuser}'@'localhost' to database 'drupal' query: LOCK TABLES faceted_search_filters WRITE in /var/www/drupal/includes/database.mysqli.inc on line 330.

Where {databaseuser} is the database user set up according to the Installation guide:

GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, INDEX, ALTER ON databasename.* TO 'username'@'localhost' IDENTIFIED BY 'password';

Since I'm new to this module, I'm not yet able to tell if or how this warning might affect the module's functionality. However, the rest of the site seems to work properly. Are there additional privileges required to run this module, or is this a bug?

Thanks & greetings, -asb