how to make line of business mandatory in incoming payment(orct) receipt if row is selected

Dear Sir 

How to marque Line Of business(OcrCode3) mandatory successful incoming outgo receipt if enactment is selected successful receipt (rct2)

i constitute codification but its not working: 

Cnt1:=0;

if :object_type='24' and (:transaction_type='A' oregon :transaction_type='U') then

SELECT Count(*) into Cnt1

FROM RCT2 T1

WHERE IFnull(T1."OcrCode3",'')= '' AND T1."IsSelected"='Y' AND T1."DocEntry" = :list_of_cols_val_tab_del;

if :Cnt1>0 then 

error := 1;           

error_message := 'You are not allowed to POST WITHOUT enactment of business';

end if;

end if;