Why I'm getting following error when excuted following script.

SCRIPT==================================
DECLARE
JobNo INTEGER;
BEGIN

DBMS_JOB.SUBMIT(:JobNo,
'E:\SQL\DataFrom400.sql',
SysDate,
'SysDate + 1/24');
END;
/
--Statement processed.
print JobNo
=====================================

ERROR=================================

SQL> @ e:\sql\x.sql
DECLARE
*
ERROR at line 1:
ORA-06550: line 1, column 94:
PLS-00103: Encountered the symbol ":" when expecting one of the following:
:= . ( @ % ;
ORA-06512: at "SYS.DBMS_JOB", line 71
ORA-06512: at "SYS.DBMS_JOB", line 121
ORA-06512: at line 4

JOBNO
---------
======================================

KED