connection database on Bluehost

My problem is solved. And that's the solution; it can help perhaps another person.
 On my server, I configured a new database with a new name_db, new user_db and new password_db.  The problem is on Bluehost. Because bluehost hosting uses WordPress hosting as default, however when you use codeigniter framework there is a configuration to do which you do not have the hand on the mysql database configuration.  You must contact Blue host to make you this configuration. On bluehost.com, you have 2 options, either by phone or chat.