Japanese lexer when used as sub lexar not giving proper result

  Iam using global lexer with english default lexar and japanese sub lexer. While using contain search with japanese single byte charactor curresponding double byte is not displayed and vice versa.
begin
CTX_DDL.create_preference('GLOBAL_LEXER','MULTI_LEXER');
CTX_DDL.add_sub_lexer('GLOBAL_LEXER','DEFAULT','ENGLISH_LEXER');
CTX_DDL.add_sub_lexer('GLOBAL_LEXER','JAPANESE','JAPANESE_LEXER');
end;


begin
CTX_DDL.create_preference('GLOBAL_LEXER','MULTI_LEXER');
CTX_DDL.add_sub_lexer('GLOBAL_LEXER','DEFAULT','JAPANESE_LEXER');
CTX_DDL.add_sub_lexer('GLOBAL_LEXER','FRENCH','FRENCH_LEXER');
CTX_DDL.add_sub_lexer('GLOBAL_LEXER','ENGLISH','ENGLISH_LEXER');
end;