Total at the end of a report

From: Smith, Ron L. <rlsmith_at_kmg.com>
Date: Wed, 28 Jun 2000 10:24:55 -0500
Message-Id: <10542.110668@fatcity.com>

Can anyone tell me why I don't get a total at the end of this report?  

set verify off
set pagesize 55
set linesize 132
spool highwater2.txt
break on server on instance_name on report compute sum of username on report
select server Server, instance_name, max(username) Max_Users

       from     
             (select distinct sample_date, server, instance_name, count(*)
username
              from km_highwater group by server, instance_name, sample_date)

 group by server, instance_name;
spool off; Received on Wed Jun 28 2000 - 10:24:55 CDT