Oracle Database Discussions

Oracle tutorial : http://www.oracle.com/technology/pub/articles/hartley-recursive.html#4

When Executing this Query 6: Using a Recursive WITH Clause

WITH C (CNO, PCNO, CNAME) AS
(SELECT CNO, PCNO, CNAME -- initialization subquery
FROM COURSEX
WHERE CNO = 'C22' -- seed
UNION ALL
SELECT X.CNO, X.PCNO, X.CNAME -- recursive subquery
FROM C, COURSEX X
WHERE C.PCNO = X.CNO)
SELECT CNO, PCNO, CNAME
FROM C;

Error: ORA-32031: illegal reference of a query name in WITH clause

kindly suggest what need to do in case of recursion using subquery