SQL & PL/SQL

Hi,
I'm runinng the job with the function:

function do_import_job(
  p_file         varchar2
) return number is
  JobNo number;
begin
  DBMS_JOB.SUBMIT (
    job          => JobNo,
    what         => 'BEGIN rog_pck_import_2.import_file('''||p_file||'''); END;',
    next_date => sysdate,
    interval  => 'null'
  );
  commit;
  return JobNo;
end do_import_job;

The job is running good. But when it goes to the end it's still "active" and is running again within a moment. How to prevent this? I wants the job to run only once and then disapear.