Oracle Base Orddoc.getProperties example giving user-defined exception

Question

First time asking a question here, so please forgive any newbie trip-ups.

I'm attempting to get the properties of a document saved as a blob in my oracle database using orddoc.getProperties, but keep coming up against a rather unhelpful user-defined exception.

One of my co-workers has gotten ordimage.getProperties working reliably on the same database, but nothing I've tried seems to resolve the problem for documents.

For certainty, I ran the exact code example from Oracle Base to ensure that I'm calling everything correctly (see below).

Can someone please clarify what's going on here and hopefully offer a suggestion on what I could do to correct it?

SETUP:

CREATE TABLE tdoc(n             NUMBER, 
                  document      BLOB, 
                  attributes    CLOB,
                  mimetype      VARCHAR2(80),
                  format        VARCHAR2(80),
                  contentlength INTEGER)
LOB(document) STORE AS SECUREFILE;

INSERT INTO tdoc VALUES(1, EMPTY_BLOB(), EMPTY_CLOB(), NULL, NULL, NULL);
INSERT INTO tdoc VALUES(2, EMPTY_BLOB(), EMPTY_CLOB(), NULL, NULL, NULL);
INSERT INTO tdoc VALUES(3, EMPTY_BLOB(), EMPTY_CLOB(), NULL, NULL, NULL);
INSERT INTO tdoc VALUES(4, EMPTY_BLOB(), EMPTY_CLOB(), NULL, NULL, NULL);
COMMIT;

TEST SCRIPT:

DECLARE
  doc_attrib CLOB;
  ctx RAW(64) :=NULL;
  doc_data BLOB;
  doc_format VARCHAR2(160) := NULL;

BEGIN
    SELECT document,attributes INTO doc_data,doc_attrib FROM tdoc WHERE N = 1 FOR UPDATE;
   ORDSYS.ORDDoc.getProperties(ctx, doc_data, doc_attrib, doc_format);

   DBMS_OUTPUT.put_line('Size of XML Annotations ' ||
                   TO_CHAR(DBMS_LOB.GETLENGTH(doc_attrib)));
   UPDATE tdoc SET document=doc_data, attributes=doc_attrib WHERE N=1;
   COMMIT;
   EXCEPTION
      WHEN OTHERS THEN
      RAISE;
END;
/

OUTPUT:

DECLARE
*
ERROR at line 1:
ORA-06510: PL/SQL: unhandled user-defined exception
ORA-06512: at "ORDSYS.ORDDOC", line 486
ORA-06510: PL/SQL: unhandled user-defined exception
ORA-06512: at line 17


No errors.