PLS-00103: error in pl/sql code

CREATE OR REPLACE procedure proc_mgtrptdetails_mon_ca
is
begin
delete from mgtrptdetails_mon_ca;


begin
insert into mgtrptdetails_mon_ca
select
case when (to_char(processdate + (7 -(to_char(processdate, 'D') - 1)),'dd-mon-yyyy') > sysdate) then to_char(sysdate,'dd-mon-yyyy')
else to_char(processdate + (7 -(to_char(processdate, 'D') - 1)),'dd-mon-yyyy' )
end as processdate, state, status, count(polnum) as nbr, sum(annualprem+annualsd) as annualprem
from subcompenddetails
where substr(channel,1,2)='CA' and processdate > '01-oct-2004'
group by processdate,state,status;
end;
commit;
end;

it says
PLS-00103: Encountered the symbol "CASE" when expecting one of the following:

the same insert works fine from sql..

pls help