OK, I finally found it!!!!!!!!!!!!!!

select m.DES, count(d.d_id)
from m, d
where m.m_id = d.m_id(+)
and m.m_id = 1
and d.posted (+) >= to_date('27-OCT-2000','dd-mon-yyyy')
and d.posted (+) <= to_date('22-NOV-2000','dd-mon-yyyy')
group by m.DES
/

Do not know why though :-(

Thanks everyone!