It could be that it's pointing at the wrong table prefix. All your tables should have some sort of prefix like ubbt_ or something else. What you need to know is the proper table prefix that was used for your actual forums.
Once you have that, you should be able to edit the includes/config.inc.php file. You'll see a bit that says 'TABLE_PREFIX' => '???_',
You'll want to change the '???_' to the proper table prefix if it isn't correct.
