declare 
tcode varchar2(4);
   vno   varchar2(9);
   recno varchar2(3);
 srcmjcd varchar2(4);
   pnplan char(1);
   vcharged char(1);
   ddocode varchar2(4);
   grantno number(4);
   grossamt number(16,2):=0;
   grossamt1 number(16,2):=0;
    fs char(1);
  rttype char(3);
    dday number(2):=0;
 mjcd varchar(4);
 sno number:=1;
 vdate date;
 vdate1 date;

cursor c is select trea_code,rec_no,substr(v_no,2,4) hd,v_no,v_date,p_nplan,v_charged,
ddo_code,grant_no,gross_amt
from treasury.bill_ent
where
v_date between :bill_ent.v_date and :bill_ent1.v_date
and grant_no not in('REC','PAC','PEN')
order by v_no;
begin
for var in c
loop
dday:=to_number(to_char(vdate,'DD'));
      if dday>11 then
       fs:='S';
      else
       fs:='F';
      end if;
if var.rec_no='103' then
         rttype:='CON';
      end if;
      if var.rec_no='102' then
         rttype:='TA';
      end if;
      if var.rec_no='105' then
         rttype:='MIS';
      end if;
      if var.rec_no='101' then
         rttype:='EST';
      end if;
      if var.rec_no='104' then
         rttype:='DEP';
      end if;
      if var.rec_no='106' then
         rttype:='PEN';
      end if;
insert into treasury.INTR_VCH_TMP_HDR 
values('01',sno,substr(var.trea_code,1,2),substr(var.v_no,2,4),fs,var.v_no,var.v_date,
var.v_charged,var.gross_amt,0,var.ddo_code,var.p_nplan,'','','',rttype,to_number(var.grant_no),'','N'
,'','',var.gross_amt,'Remark','','Y','Y','N','Y','');
sno:=sno+1;
end loop;
commit;
end;

for var in c
loop
  MESSAGE('var.trea_code = ' || var.trea_code);

where v_date between :bill_ent.v_date and :bill_ent1.v_date
  and grant_no not in ('REC', 'PAC', 'PEN')

WHERE v_date between to_date(:bill_ent.v_date, 'dd.mm.yyyy') and ...

sql statement in error:
INSERT INTO BILL_ENT(V_DATE) VALUES (:1)  

error:
ORA-01400: cannot insert NULL into ("TREASURY"."BILL_ENT"."TREA_CODE")