I found what's wrong. In php.ini setting of php4 version, it is set up--register_globals=On, but in php5 version
it is set up--register_globals=Off. Please upload .htaccess file attached in public_html directory.
Before sign_up, first you need to create an admin account by entering:
http://your_domain.coom/install.php.
Then, an admin account will be created with username of 'admin', real name of 'Administrator' and the
password you entered. After creating admin account, plese do login test with the username 'admin' and
your password.