如何修复DomPDF纸张尺寸更改但仍为默认尺寸

Question

我在使用Dom PDF库进行编码时将纸张尺寸更改为f4时遇到问题，尺寸仍然为Default Legal。这是我的图书馆代码

                $layout=$this->Surat_template_model->get_surat_template_row($template_id);
                $kop=$this->Kop_surat_model->get_kop_surat($this->input->post('surat_kop_id'));
                $ttd=$this->get_footer_tinjau_naskah();
                //Loading Data
                $data['kop']='upload/kop/'.$kop['kop_url'];
                $data['ttd']=$ttd;
                $this->load->view('admin_surat/layout_surat/'.strtolower(url_title($layout['surat_template_name'],'_')).'/index',$data);

                $html = $this->output->get_output();

                // Load pdf library
                $this->load->library('pdf');

                // Load HTML content
                $this->pdf->loadHtml($html);
                // (Optional) Setup the paper size and orientation
                $this->pdf->setPaper('f4', 'potrait');
                // Render the HTML as PDF
                $this->pdf->render();

                // Output the generated PDF (1 = download and 0 = preview)
                $this->pdf->stream("Download.pdf", array("Attachment"=>0));

我需要帮助..谢谢