Should you not have a value in CFG->dbpass = ''; (My server has died so I cannot look, right now. I am pretty certain that I have a value on that line in my config.php file.)
Thanks for your reply Collin. Actullly I always put CFG->dbpass as null and $CFG->dbuser as 'root'. So I think that's not the problem.
My problem solved.Its related to db error.