[Exim4U] PHP Fatal error: Class 'DB' not found

Dear all, Was installing the exim4u in a new server but encounter the below error: PHP Fatal error: require_once(): Failed opening required 'DB.php' (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/exim4u/config/variables.php on line 3 The php version am using is PHP 5.4.4-14+deb7u7, it looks like the DB.php is no more in the /usr/share/php. i have another previous installation which is running php version 5.3.3. Debian or PHP5 must have change something and miss things up, i might try to work on a fix later on just too busy right now. Thanks Kebba