继续问，为什么预览时出错：QRPrinter not ready?

procedure TFormClassPrint.QuickRepMainPreview(Sender: TObject);
begin
  inherited;
  QuickRepMain.Prepare;
  QuickRepMain.PreviewModeless;
  with TFormClassRepPreview.Create(Application) do
  begin
    QRPreviewPreview.QRPrinter := QuickRepMain.QRPrinter;
    Hide;
    ShowModal;
  end;
end;
在TFormClassRepPreview.ShowModal;后将页面关闭时报出的错误。