The character set WE8ISO8859P1 needs to either be the default on the server the ADU is running on, or the Control file needs to be updated with the Character set.

Here is an example of lines from a Control file:

OPTIONS (ROWS = 500, BINDSIZE = 51100, ERRORS = 99999)
LOAD DATA
APPEND


To update the Control file, add the following line (CHARACTERSET WE8ISO8859P1) here:

OPTIONS (ROWS = 500, BINDSIZE = 51100, ERRORS = 99999)
LOAD DATA
CHARACTERSET WE8ISO8859P1
APPEND


Use the following query to find the default Oracle Character Set for the database:

SELECT DB.PARAMETER, DB.VALUE DB_VALUE, INS.VALUE INSTANCE_VALUE, SES.VALUE SESSION_VALUE
FROM   (SELECT *
        FROM   NLS_DATABASE_PARAMETERS) DB,
      (SELECT *
        FROM   NLS_INSTANCE_PARAMETERS) INS,
      (SELECT *
        FROM   NLS_SESSION_PARAMETERS) SES
WHERE  DB.PARAMETER = INS.PARAMETER(+)
      AND DB.PARAMETER = SES.PARAMETER(+);


The Parameter to notice is "NLS_CHARACTERSET".