Problem ending setup with airtime-install.php

hello everyone,
I come from France, I've searched on FAQ and on google but I can't solved my problem.
I'm on dedicated server using Debian Squeeze and PostgreSQL 8.4

when I try to execute airtime-install.php with root, it return me this error

******************************** Install Begin *********************************
 *** Database Installation ***
   * User airtime already exists.
   * Database 'airtime' already exists.
DB Error: connect failed
 [nativecode=pg_pconnect(): Unable to connect to PostgreSQL server: FATAL:  authentification par mot de passe échouée pour l'utilisateur  << airtime >>
FATAL:  authentification par mot de passe échouée pour l'utilisateur  << airtime >>] ** pgsql(pgsql)://airtime:PASSWORD@localhost/airtime
Database connection problem.
Check if database 'airtime' exists with corresponding permissions.

It say in french that it can't auth because password failed..

when I use the command psql -l, it return me this

                             Liste des bases de données
    Nom    | Propriétaire | Encodage |  Tri  | Type caract. |    Droits d'accès
-----------+--------------+----------+-------+--------------+-----------------------
 postgres  | postgres     | LATIN1   | fr_FR | fr_FR        |
 template0 | postgres     | LATIN1   | fr_FR | fr_FR        | =c/postgres
                                                            : postgres=CTc/postgres
 template1 | postgres     | LATIN1   | fr_FR | fr_FR        | =c/postgres
                                                            : postgres=CTc/postgres
(3 lignes)

can't see airtime db ou user...

Did I miss somethings..

Thanks for reading and try to help me

Cheers!