ORA-21560: argument 3 is null, invalid, or out of range

help experts!  i'm getting this error when i am running the below procedure.  however, i do not get this error on a consistent basis.  sometimes the process runs fine.  other times i get this error, so i don't think it's a code problem.  this is leading me to think that it is occuring as result of some limitation (memory, number of processes allowed, etc) on either my database or server (hp unix).  can someone give me an idea as to what could be causing this?  can you think of some system settings that i could raise to avoid this?


 ORA-21560: argument 3 is null, invalid, or out of range


CREATE OR REPLACE PROCEDURE botables_proc (
   p_tablename    VARCHAR2,
   p_xml_dir      VARCHAR2,
   p_parse_name   VARCHAR2,
   p_reqid        NUMBER
)
IS
   v_in_handle         SYS.UTL_FILE.file_type;
   v_insctx            SYS.dbms_xmlsave.ctxtype;
   n_rows              NUMBER;
   n_row_flag          NUMBER                   := 0;
   n_parse_file_flag   NUMBER                   := 0;
   n_record_count      NUMBER                   := 0;
   v_clob              CLOB;
   v_bfile             BFILE;
   n_amt               BINARY_INTEGER;
   v_offset            INTEGER                  := 1;
   c_xml_row           VARCHAR2 (32767)         := 'XXX';
   n_substr_amount     INTEGER;
   n_instr_offset      INTEGER                  := 1;
   n_dest_offset       NUMBER                   := 1;
   n_src_offset        NUMBER                   := 1;
   n_lang_ctx          NUMBER                   := DBMS_LOB.default_lang_ctx;
   n_bfile_csid        NUMBER                   := SYS.DBMS_LOB.default_csid;
   n_warning           NUMBER;
BEGIN
          --sets context handle to reference table
         v_insctx := SYS.dbms_xmlsave.newcontext (p_tablename);
   --sets incoming date format
   SYS.dbms_xmlsave.setdateformat (v_insctx, 'yyyy-MM-dd HH:mm:ss');
   --ignores case differences between tags and column names
   SYS.dbms_xmlsave.setignorecase (v_insctx, 1);
   --create a bfile using the xml directory created by the DBA.
   v_bfile := BFILENAME ('XML', p_reqid || '_INSERT_' || p_parse_name);
   --create a temporary lob.  this lob resides in RAM for the
   --duration of the session.
   SYS.DBMS_LOB.createtemporary (v_clob, TRUE, DBMS_LOB.SESSION);
   --open the temporary lob for read/write.  this is done implicitly
   --by oracle, but is being left as a comment for reference so it is known
   --that this step was not skipped.
   --SYS.DBMS_LOB.OPEN (v_clob, SYS.DBMS_LOB.lob_readwrite);
   --get the length of the bfile so you know how much space
   --you need to open it.
   n_amt := DBMS_LOB.getlength (v_bfile);
   --open the bfile for reading
   SYS.DBMS_LOB.fileopen (v_bfile, SYS.DBMS_LOB.file_readonly);
   --load the contents of the bfile into the temporary lob
   SYS.DBMS_LOB.loadclobfromfile (v_clob,
                                  v_bfile,
                                  n_amt,
                                  n_dest_offset,
                                  n_src_offset,
                                  n_bfile_csid,
                                  n_lang_ctx,
                                  n_warning
                                 );
   --create a table context to save to
   v_insctx := SYS.dbms_xmlsave.newcontext (p_tablename);
   --set the date format for the insert
   SYS.dbms_xmlsave.setdateformat (v_insctx, 'yyyy-MM-dd HH:mm:ss');
   --set the package to ignore case
   SYS.dbms_xmlsave.setignorecase (v_insctx, 1);

   --while the end of the clob (xml file) has not been reached,
   --read it line by line and insert and lines that contain "<ROW>"
   --into the table.
   WHILE c_xml_row NOT LIKE '%</ROWSET>%'
   LOOP
      n_substr_amount :=
               (SYS.DBMS_LOB.INSTR (v_clob, CHR (10), n_instr_offset, 1) - 1
               );
      n_substr_amount := n_substr_amount - n_instr_offset + 1;
      c_xml_row :=
                 SYS.DBMS_LOB.SUBSTR (v_clob, n_substr_amount, n_instr_offset);

      IF c_xml_row LIKE '%<ROW>%'
      THEN
         BEGIN
            n_rows := SYS.dbms_xmlsave.insertxml (v_insctx, c_xml_row);
         EXCEPTION
            --any exception that is encased in the oracle java exception -29532 will be searched
            --for the strings indicating that an index or constraint were violated.  if these
            --strings are found, then nothing will happen because those errors will intentionally
            --occur frequently due to the indexes and constraints that have been added to the
            --ODS tables.
            WHEN OTHERS
            THEN
               IF    INSTR (SQLERRM, 'ORA-00001', 1) > 0
                  OR INSTR (SQLERRM, 'ORA-01400', 1) > 0
               THEN
                  NULL;
               ELSE
                  DBMS_OUTPUT.put_line (   'Error inserting to table '
                                        || p_tablename
                                        || ' by file '
                                        || p_parse_name
                                       );
                  DBMS_OUTPUT.put_line (   'Bad XML Line: '
                                        || SUBSTR (c_xml_row, 1, 225)
                                       );
                  DBMS_OUTPUT.put_line ('ERROR:  ' || SUBSTR (SQLERRM, 1, 175));
                  DBMS_OUTPUT.put_line ('');
               END IF;
         END;
      END IF;

      n_instr_offset := n_instr_offset + n_substr_amount + 1;
   END LOOP;

   --close the open file handles an lob and free the resources used.
   SYS.dbms_xmlsave.closecontext (v_insctx);
   SYS.DBMS_LOB.fileclose (v_bfile);
   SYS.UTL_FILE.fclose (v_in_handle);

   --the dbms_lob.close is not needed for temporary lobs and
   --the freetemporary call is done implicitly by the
   --dbms_lob.session parameter in the createtemporary call above.
   --both statements are being left as comment so it is known that
   --these steps were not skipped.
   --SYS.DBMS_LOB.CLOSE (v_clob);
   --SYS.DBMS_LOB.freetemporary (v_clob);

   --insert a count of the total records inserted by a report
   INSERT INTO ems_owner.rpt_sltn_err_lly
        VALUES (p_parse_name, SYSDATE, n_record_count);

   COMMIT;
EXCEPTION
   --in case of any error encountered, close the open file
   --handles an lob and free the resources used.
   WHEN OTHERS
   THEN
      SYS.dbms_xmlsave.closecontext (v_insctx);
      DBMS_LOB.fileclose (v_bfile);
      SYS.UTL_FILE.fclose (v_in_handle);
      --the dbms_lob.close is not needed for temporary lobs and
      --the freetemporary call is done implicitly by the
      --dbms_lob.session parameter in the createtemporary call above.
      --both statements are being left as comment so it is known that
      --these steps were not skipped.
      --SYS.DBMS_LOB.CLOSE (v_clob);
      --SYS.DBMS_LOB.freetemporary (v_clob);
      DBMS_OUTPUT.put_line (SQLERRM);
      COMMIT;
END;
/