SQL & PL/SQL

i created a procedure proc1 in user scott which inserts a sequence of numbers into the table called 'ss' .

create or replace procedure proc1(a in number) is
begin
insert into ss values(seq1.nextval);
end;


Later i tried to run the dbms_job .submit from the sys user in the following way:

variable jobno number;

BEGIN
DBMS_JOB.isubmit (
:jobno,
what => 'scott.proc1(3);',
next_date => SYSDATE,
interval => 'SYSDATE + 1/144 /* 1 Hour */');

COMMIT;
END;
/

I am getting the error :

BEGIN
*
ERROR at line 1:
ORA-01407: cannot update ("SYS"."JOB$"."JOB") to NULL
ORA-06512: at "SYS.DBMS_JOB", line 97
ORA-06512: at line 2


can anybody help me.