🚀 go-pugleaf

I apologise for this trouble of making a repost but I couldnt find a 
solution
anywhere on the net or on codegear.
Im developing a db app. I use third party database and their components as
well which are compatible with delphi datasets. When a purchase is made in
the app. records are tallyed with inventory and inventory is updated and/or
new records are inserted accordingly. I used BeforePost event to tally
inventory with purchase cause AfterPost will not give the record status
after they are posted. Before records are posted I want to check if the
record is new or modified based on that i'll update the inventory. Here's
the code:

procedure TMastData.TPDetailsBeforePost(DataSet: TDataSet);
begin
  { First prepare inventory query }
  QCSelect.SQL.Clear;
  QCSelect.SQL    := QryStore.ItemByName['InventoryByID'].Strings;
  QCSelect.ParamByName('p_itemid').AsInteger := TPDetailsf_itemid.Value;
  QCSelect.Active := True;

  { If a new record then insert it in inventory }
  if DataSet.UpdateStatus = usInserted then
  begin

  end;
  { If record modified then just update inventory }
  if DataSet.UpdateStatus = usModified then
  begin
    { Check current item with inventory item }
    if TPDetailsf_itemid.Value = QCSelect.FieldByName('f_itemid').AsInteger
then
    begin
      with QCUpdate do
      begin
        SQL.Clear;
        SQL    := QryStore.ItemByName['UpdtFrmPurchaseMast'].Strings;
        { Setup parameters }
        ParamByName('p_item').Value := TPDetailsf_item.Value;
        ParamByName('p_code').Value := TPDetailsf_code.Value;
        ParamByName('p_group').Value := TPDetailsf_group.Value;
        ParamByName('p_pdate').Value := TPMasterf_date.Value;
        ParamByName('p_size').Value := TPDetailsf_size.Value;
        ParamByName('p_unit').Value := TPDetailsf_unit.Value;
        ParamByName('p_rate').Value := TPDetailsf_rate.Value;
        ParamByName('p_qty').Value := TPDetailsf_acceptedqty.Value;
        ParamByName('p_tax').Value := TPDetailsf_tax.Value;
        ParamByName('p_amount').Value := TPDetailsf_amount.Value;
        ParamByName('p_itemid').AsInteger := TPDetailsf_itemid.Value;
        { Execute the query }
        Active := True;
        Prepare;
        ExecSQL;
        Active := False;
      end;
    end;
  end;
  if DataSet.UpdateStatus = usDeleted then
  begin

  end;
  { Close queries and move to next record }
  QCSelect.Active := False;
end;

When I check the status of record during debugging it shows usUnmodified???
I don't know how and why this is happening.
If you guys have any idea then I'd thank you in advance. One more thing that
I have not used client datasets for cached updates
in this app either.