Dbms_submit Errors

[learning_bee]

var x number
begin
dbms_job.submit(:x, 'MY_PROCEDURE;', TRUNC(sysdate)+19/24, 'TRUNC(sysdate)+1+19/24');
commit;
end;
/

begin
*
ERROR at line 1:
ORA-06550: line 1, column 93:
PLS-00306: wrong number or types of arguments in call to 'MY_PROCEDURE'
ORA-06550: line 1, column 93:
PL/SQL: Statement ignored
ORA-06512: at "SYS.DBMS_JOB", line 79
ORA-06512: at "SYS.DBMS_JOB", line 136
ORA-06512: at line 2


what's wrong with my job scheduling???