มีปัญหาเรื่อง upload รูปภาพไม่เก๊บอยู่ใน folder ที่กำหนดครับ

<div id="bodyone">
<form action="run_admin_add.php" method="post" enctype="multipart/form-data" name="frm002"> 

<table border="0"><tr><td>
  <label>หัวข้อเรื่อง: </label></td>
  <td><input name="txt_subject" id="txt_subject" type="text" /></td>
  <br />

<tr><td><label>รูปภาพ : </label></td>
  <td><input type="file" name="filename">
  </td>
  </tr>
<tr>
<td>เนื้อหา :</td>
<td><label for="txr_content"></label>
  <textarea name="txr_content" id="txr_content" cols="45" rows="5"></textarea></td>
</tr>
<tr>
<td colspan="2" align="center">
<input name="btnsave" id="btnsave" type="submit" value="Save" />
<input name="btnreset" id="btnreset" type="reset" value="Reset" />
</td>
</tr>
  </table>
</form>

</div>

<?
include "connect.php";
$txt_subject=$_POST['txt_subject'];
if ($txt_subject==""){$txt_subject=$_GET['txt_subject'];}
$txr_content=$_POST['txr_content'];
if ($txr_content==""){$txr_content=$_GET['txr_content'];}
?>
<?
if($txt_subject=="" && $txr_content==""){
	echo "กรอกข้อมูลไม่ครบครับ";
	exit();
	}

$photo_user=$_FILES[ 'photo_user'] ['tmp_name'];
$photo_user_name=$_FILES[ 'photo_user'] ['name'];
$photo_user_size=$_FILES[ 'photo_user'] ['size'];
$photo_user_type=$_FILES[ 'photo_user'] ['type'];

$ext = strtolower (end(explode('.', $photo_user_name)));

$Sql="select  max(id)  from learning_center";	
		$result=mysql_db_query($dbname,$Sql);
		while($r=mysql_fetch_array($result))
		{	$id_max=$r[0];
			  $filename=$id_max.".".$ext;
				copy($photo_user_name,"pic_user/$filename");
				}
	$Sql="INSERT INTO learning_center(subject,content,pic) values ('$txt_subject','$txr_content','$filename')";
$query=mysql_query($Sql);
echo $Sql;
?>