SQL & PL/SQL :: Save Point Is Not Working?

In oracle 9i, I have a table and i inserted the more then 3 records and while inserting each records i have created the save point. But, now i rollback to that particular save point, the whole transaction get roll backed.

Here the similar example what i have tried using SQL Developer Eg:

insert into dept (deptid,dept_name) values (3,'Purchase');
savepoint aa;
insert into dept (deptid,dept_name) values (4,'IT');
savepoint bb;
insert into dept (deptid,dept_name) values (5,'System');
savepoint cc;
rollback to bb;