Problems connecting to external database

I read in another thread on the support forum about creating a separate template for a page I want to use to connect to an external database. So I did that and it works fine when testing locally with my XAMPP installation, but when I upload everything to the server, I’m getting these errors generated from header.php:

WordPress database error: [Table ‘name-of-external-db.wp_terms’ doesn’t exist]
WordPress database error: [Table ‘name-of-external-db.wp_posts’ doesn’t exist]
WordPress database error: [Table ‘name-of-external-db.wp_options’ doesn’t exist]

in other words the table names from the WP db are being appended to my external db. Anyone know a way around this?