DATABASE ERROR: CONNECTION FAILED!

[oaram]

Hello to all.
After I installed roundcube, it says:
DATABASE ERROR: CONNECTION FAILED!

Unable to connect to the database!
Please contact your server-administrator.
I restart mysql,http,postfix,roundcube but the message still there!
Please help me.

[SKaero]

Check the database information in the db.inc.php and make sure it is correct.