Oracle - CREATE OR REPLACE MATERIALIZED VIEW

I want to create/replace the materialized view but i got the following error
ORA-00922 - Missing or invalid option

CREATE OR REPLACE MATERIALIZED VIEW payroll_mvw
REFRESH ON DEMAND
AS SELECT payroll_no
      ,employee_no
      ,employee_name
      ,department
FROM payroll
WHERE payroll_date >= to_date('01-JUL,2000','DD-MON-YYYY')
ORDER BY employee_no
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I refer to the following link=
http://www.oracle.com/technology/oramag/oracle/05-mar/o25data.html

I run ok if i remove the REPLACE, like below

CREATE MATERIALIZED VIEW payroll_mvw
REFRESH ON DEMAND
AS SELECT payroll_no
      ,employee_no
      ,employee_name
      ,department
FROM payroll
WHERE payroll_date >= to_date('01-JUL,2000','DD-MON-YYYY')
ORDER BY employee_no

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My question is why i can't use 'CREATE OR REPLACE', but the oracle's example indicates we can use