i think i might know what your problem is, since the same sort of thing happened to me.
anyway, here is one of the lines from the file wp-config-sample.php that you should have modified:
define(‘DB_NAME’, ‘wordpress’);
this needs to be changed to:
define(‘DB_NAME’, ‘(actual_db_name’);
i, apparently suffering from a particularly smelly brain fart, originally modified the wp-config.php file to look like this:
define(‘(actual_db_name)’, ‘wordpress’);
hope that helps!