data query question

Hello everyone:
I have a question about a query dealing with dates. This is my origina query:
select distinct to_char(question_date,'DD-MON-YYYY') from student_profile where student_id = 10;
I get the following results:

04-JAN-2001
05-JAN-2001
07-NOV-2000
08-NOV-2000
09-JAN-2001
14-NOV-2000
15-DEC-2000
15-NOV-2000
18-JAN-2001
19-DEC-2000
20-DEC-2000
21-DEC-2001

I am getting the correct results, but not in the order I expected (chronological order). I have tried "order by question_date' but no success.

Thanks in advance!

--------------Claudia V. Casas-----------------