Oracle Database Express Edition (XE)

Was working on tutorial from the:

Oracle Database Express Edition 2 Day Plus Application Express Developer Guide

Working on the section 4: How to Control Form Layout.

Ran into a problem trying to compile the Create HT-EMP Table script.

keep getting this error for this particular segment creating the bu_ht_emp trigger:
pp. 4-2 and 4-3

CREATE OR REPLACE TRIGGER bi_ht_emp
BEFORE INSERT ON ht_emp
FOR EACH ROW
BEGIN
SELECT ht_emp_seq.nextval
INTO :new.emp_id
FROM DUAL;
:new.rec_create_date := SYSDATE;
END;
/
ORA-06502: PL/SQL: numeric or value error ORA-06512: at "SYS.OWA_UTIL", line 354....etc

I've check the syntax for the entire script and it all checks out. Does anyone have a clue why this is failing?