Quoting Chris Johnson cxjohnson@gmail.com:
You don't need to use $db_prefix to use multiple databases. It has an
This isn't the cause of the problem.
entirely different purpose. It's job is prefix the table names within a given database to prevent collision with other tables of the same name, perhaps being used by another application, or by multiple instances of Drupal sharing the same database. It's mostly there to help folks who have low-end hosting arrangements and have one or limited databases.
It's mostly there so that you can prefix table names. If the table names are prefixed then $db_prefix needs to be set.
Earnie -- http://for-my-kids.com/ -- http://give-me-an-offer.com/