APEX

have a master-detail page, wrote process for line items to save data, when trying to Save it is showing ORA-01722: invalid number
how i can display below values so i can know where is the error? please help.

declare
v_code number;
o_code number := 0;
begin
   case :APEX$ROW_STATUS
        when 'C' then
            Select Nvl(Max(IL_TRANS_LN),0)+1 
              Into v_code 
              from INV_LN 
             WHERE IL_TRANS_CODE = :P182_IH_TRANS_CODE AND IL_FLAG = 'OPEN';
             insert into INV_LN(IL_ORG_ID, IL_TRANS_CODE, IL_TRANS_LN, 
                                IL_ITEM_MODEL, IL_ITEM_LOCATION, ITEM_DESC, 
                                IL_ITEM, IL_UOM, IL_RULE, IL_QTY, IL_UNIT_COST,
                                IL_REMAKRS, IL_CRE_BY, IL_CRE_DATE, IL_AMOUNT, 
                                IL_UNIT_PRICE, IL_OPEN_CODE, IL_FLAG)
             values            (:SESSION_BUS_UNIT, :P182_IH_TRANS_CODE, V_CODE, 
                                :IL_ITEM_MODEL, :IL_ITEM_LOCATION, :ITEM_DESC,
                                :IL_ITEM,:IL_UOM, :IL_RULE, :IL_QTY, :IL_UNIT_COST,
                                :IL_REMAKRS, :APP_USER, SYSDATE, :IL_AMOUNT, 
                                :IL_UNIT_PRICE, :P182_IH_TRANS_CODE, 'OPEN')
             returning v_code into :IL_TRANS_LN;
        end;
    end case;
end;

regards