CdvPHP Framework Db Error

Error messages:

[Type] 无法连接到数据库服务器

Program messages:

[Line: 0017]/home/dahai/webapps/lijing/index.php(class_core::_get_instance) [Line: 0034]class/core.php(class_core->__construct) [Line: 0058]class/core.php(class_core->_dispatch) [Line: 0298]class/core.php(main->products_details_action) [Line: 0470]control/main.php(db::isobject) [Line: 0563]class/core.php(db::_object) [Line: 0593]class/core.php(db_mysql->connect) [Line: 0403]class/core.php(db_mysql->_dbconnect)