i think it is a configuration problem. the best way to verify this is to make a phpinfo page
PHP Code:
<?
phpinfo();
?>
about 3/4 the way down you should see a table with MYSQL at the top. if you don't, then mysql support has not been added with your php install.
i'm not familiar with mandrake, .. i might assume it is an rpm type of os.
i know for redhat and debian, the package name for this is 'php-mysql'
even then, getting all of them to install correctly is tricky.
was mysql installed first? it should be installed before apache and php.
i wish i was more familiar with mandrake