NLS_LANGUAGE issue at database installation

Hello,
I'm installing Oracle database software 11.2.0.4 on an AIX 6.1 box

Then i'm creating an instance with the following character sets:

• Database character set: WE8ISO8859P15 - Western Europe
• National character set: AL16UTF16
• Default language: French
• Date format: France

But when i query NLS_DATABASE_PARAMETERS, the American language appears:

SQL> select * from nls_database_parameters;

PARAMETER                      VALUE
------------------------------ ----------------------------------------
NLS_LANGUAGE                   AMERICAN
NLS_TERRITORY                  AMERICA
NLS_CURRENCY                   $
NLS_ISO_CURRENCY               AMERICA
NLS_NUMERIC_CHARACTERS         .,
NLS_CHARACTERSET               WE8ISO8859P15
NLS_CALENDAR                   GREGORIAN
NLS_DATE_FORMAT                DD-MON-RR
NLS_DATE_LANGUAGE              AMERICAN
NLS_SORT                       BINARY
NLS_TIME_FORMAT                HH.MI.SSXFF AM