distinct

I have attempted to run 
select distinct col1 from tablename;
and it runs fine.

When I run it in a real world environment:
select distinct col1, col2, col3, col4 from tablename order by col1 desc,
col2;
It returns all the values from col1 which appears to be the same thing as
not using distinct at all.

Am I missing something? I'd like only distinct values on col1 and then I'll
sort, include, or exclude the other columns.

Andrew