RoundCube "DATABASE ERROR: CONNECTION FAILED" on second domain

Version 3.69
Ubuntu Ubuntu Linux 8.04

I install roundcube (from virtualmin) on a first domain www.berrezay.net/roundcube and it works perfectly.

I install roundcube (from virtualmin) on a second domain www.froissart.net/roundcube and
, I can only get a page with the following error:

DATABASE ERROR: CONNECTION FAILED!

Unable to connect to the database!
Please contact your server-administrator.

MySQL is up and running, and the roundcube database seems to be ok...

pear list
Installed packages, channel pear.php.net:
=========================================
Package Version State
Archive_Tar 1.3.2 stable
Console_Getopt 1.2.3 stable
DB 1.7.13 stable
PEAR 1.6.1 stable
Structures_Graph 1.0.2 stable

php5-mysql is installed

Status: 
Closed (fixed)