oracle markup drsxsopen error

Hi!

I'm getting errors whenever I try to call ctx_doc.markup in my stored procedure. Here's my stored procedure:

Code:

---

  function testFunc(anEmpId in varchar2) return varchar2
  is
    clMarkedUpText clob;
    vSurname varchar2(100);
  begin
    ctx_doc.markup(
      'EMPLOYEE$FREE_TEXT',
      anEmpId,
      'FOO',
      clMarkedUpText,
      FALSE,
      'HTML_DEFAULT',
      '',
      ''
    );   
    return 'SUCCESS';
  exception
    when others then
      return sqlerrm;
  end testFunc;

---

Here's the sql statement:
SELECT testFunc(EMP_ID) STOREDPROC_SUCCESS FROM EMPLOYEE


Here's the error message:
ORA-20000: Oracle Text error:
DRG-50857: oracle error in drsxsopen
ORA-00904: "SYS_NC00031$": invalid identifier


If I execute the command in toad, the value returned by the function is 'SUCCESS'. If
it is executed within my java application, it returns sqlerrm. The index is created with:

CREATE INDEX EMPLOYEE$FREE_TEXT on EMPLOYEE(XML_COLUMN)
INDEXTYPE IS CTXSYS.CONTEXT PARAMETERS('LEXER MYLEXER STOPLIST MYSTOPLIST WORDLIST MYWORDLIST');

FYI: I'm using oracle 10g.

Any help would be appreciated. I haven't got a clue on how to fix this. =(