ช่วยดูโค้ดให้หน่อยครับ เกี่ยวกับฟังก์ชั่น copy Error : failed to open stream: Permission denied in

<?php 
session_start();
if ($_SESSION[sess_userid]<>session_id()) {
	header("Location: admin.php"); exit();
}
$title=$_POST['title'];
$detail=$_POST['detail'];
$type=$_POST['type'];

$photo=$_FILES['photo']['tmp_name'];
$photo_name=$_FILES['photo']['name'];
$photo_size=$_FILES['photo']['size'];
$photo_type=$_FILES['photo']['type'];

$_pdf=$_FILES['_pdf']['tmp_name'];
$_pdf_name=$_FILES['_pdf']['name'];
$_pdf_size=$_FILES['_pdf']['size'];
$_pdf_type=$_FILES['_pdf']['type'];

$date_today=date("Y-m=d");
$time_today=date("H:i:s");

if ($title=="" or $detail=="" or $type=="0") {
		echo "<h2> กรุณากรอกข้อมูลให้ครบ </h2>";
		exit();
}
include "connect.php";
$sql="INSERT INTO tb_new VALUES (null, '$title', '$detail', '$type', '', '', '$date_today', '$time_today')";
mysql_db_query ("$dbname", $sql);

$ext = strtolower(end(explode('.', $photo_name)));
if ($ext == "jpg" or $ext == "jpeg" or $ext == "png" or $ext == "gif") {
		
		$sql = "select max(id_new) from tb_new";
		$result = mysql_db_query($dbname, $sql);
		$r = mysql_fetch_array($result);
		$id_max = $r[0];
		
		$filename = $id_max.".".$ext;
		copy($photo,"photo/$filename");
		
		$sql = "update tb_new set photo_new='$filename' where id_new='$id_max' ";
		mysql_db_query($dbname, $sql);
}
$ext= strtolower(end(explode('.', $_pdf_name)));
if ($ext == "pdf") {

		$sql = "select max(id_new) from tb_new";
		$result = mysql_db_query($dbname, $sql);
		$r = mysql_fetch_array($result);
		$id_max = $r[0];

		$filenamepdf = $id_max.".".$ext;
		copy($_pdf,"_pdf/$filenamepdf");
		
		$sql = "update tb_new set pdf_new='$filenamepdf' where id_new='$id_max' ";
		mysql_db_query($dbname, $sql);
}
echo "<h3>เพิ่มข้อมูลเรียบร้อยแล้วครับ</h3>";
echo "[ <a href=new_main.php>กลับหน้าหลัก</a> ] ";
mysql_close();
?>