Oracle Forms

hi master

Sir I use this code in post query event


:partyname :='';
:CHQBANK :='';
:repchq:='';
:chqdate:=null;
:chqbank:='';
:PARTYNAME :='';

select YEARID,TITLE,STDATE,CLDATE,CLOSINGSTATUS into :yearid,:yeartitle,:ysdate,:yedate,:YSTATUS from yeartable where stdate<=:entdate and cldate>=:entdate;
if :partyid is not null then
select title into :PARTYNAME from partytable where partyid=:partyid;
end if;


:repchq :=substr(:cheqno,10,8);

if :CHEQNO is not null then
SELECT nvl(CHARTOFACC.title,' ') INTO :chqbank FROM CHEQMASTER,CHEQDETAIL,CHARTOFACC WHERE CHEQDETAIL.serialid=CHEQMASTER.serialid AND CHEQMASTER.accid=CHARTOFACC.accid and CHEQDETAIL.CHEQNO=:CHEQNO;

end if;


sir when :CHEQNO not null system give me right result but when :CHEQNO is null then system give me this error


FRM-40735: POST-QUERY trigger raised unhandled exception ORA-01403

If I revome this code

if :CHEQNO is not null then
SELECT nvl(CHARTOFACC.title,' ') INTO :chqbank FROM CHEQMASTER,CHEQDETAIL,CHARTOFACC WHERE CHEQDETAIL.serialid=CHEQMASTER.serialid AND CHEQMASTER.accid=CHARTOFACC.accid and CHEQDETAIL.CHEQNO=:CHEQNO;
end if;
then system run right
please give me idea how I solve this error

thank
aamir