Database Software

I'm having an issue with external tables, that I don't understand. Hoping somebody can help me out?

Here is how I create the external table.

CREATE TABLE TBLTMP_MES1_MATERI_MASTER_DATA
   ( "MARC_WERKS" VARCHAR2(4 CHAR),
  "MARA_MATNR" VARCHAR2(18 CHAR),
  "MARA_MAKTX" VARCHAR2(40 CHAR),
"MARC_ZIV_PRDSTOP" VARCHAR2(1 CHAR)
   )
   ORGANIZATION EXTERNAL
    ( TYPE ORACLE_LOADER
      DEFAULT DIRECTORY "ENDERECO_REDE_INBOUND"
      ACCESS PARAMETERS
      ( records delimited by '\n'
      CHARACTERSET UTF8
    NOLOGFILE
    FIELDS LRTRIM
  MISSING FIELD VALUES ARE NULL (
      MARC_WERKS POSITION (1:4) CHAR,
      MARA_MATNR POSITION (5:22) CHAR,
      MARA_MAKTX POSITION (28:67) CHAR,
      MARC_ZIV_PRDSTOP POSITION (357:357) CHAR
    )
                      )
      LOCATION
       ( "ENDERECO_REDE_INBOUND":'MES1.txt'
       )
    )
   REJECT LIMIT UNLIMITED;

The file is a utf8 without BOM (verified with a Hex Editor),  the word 'JUN¸AO' in Hex editor is '4A 55 4E C2 B8 41 4F'.

The external table write in the .bad file all lines that have words with accent like ã, ç, í and so on...

I already create a file with different charset like ISO-8859-1 and changed the charset of the create table script to WE8ISO8859P1 and works.

Are there some problem with loading UTF8 file?

Could someone explain what I missing?

Thanks in advance.