php.activerecord

Subject: Hi, please help me with my php codes

I cannot upload my file that is sent by another page. here is my code:

/** * @author alireza

• trpr.ir * @copyright 2015
  */

require_once ('database.php');
$sender_page='../news.php';
if($_GET['t']=="delete") {
if(!isset($_GET['id']))
exit('<meta http-equiv="refresh" content="0;url='.$sender_page.'">');
if(!is_numeric($_GET['id']))
exit('<meta http-equiv="refresh" content="0;url='.$sender_page.'">');

$sql_update="DELETE FROM `tbl_news` WHERE `id`='".$_GET['id']."'";
    $result_update=$connect->prepare($sql_update);
    $result_update->execute();
    security::Redirect("../news_list");
}
//---------- insert and update
$filename=$_FILES['file']['name'];
$file = md5($filename.microtime()).substr($filename,-5,5);
move_uploaded_file($_FILES['file']['tmp_name'],"./news/".$file);

$arr = array(':title' => $_POST['title'],
':writer' =>$_POST['writer'],
':shortdesc' =>$_POST['shortdesc'],
':longdesc' =>$_POST['longdesc'],
':date' =>$_POST['date'],
':img' =>$file );
if($_GET['t']=='new') {

$sql="INSERT INTO `tbl_news`(title,writer,shortdesc,longdesc,date,img)
VALUES (:title,:writer,:shortdesc,:longdesc,:date,:img)";
$result=$connect->prepare($sql);
$query=$result->execute($arr);
die('ok');
}else if($_GET['t']=="edit") {
if(!isset($_GET['id']))
exit('<meta http-equiv="refresh" content="0;url='.$sender_page.'">');
if(!is_numeric($_GET['id']))
exit('<meta http-equiv="refresh" content="0;url='.$sender_page.'">');

$title=$_POST['title'];
                            $writer=$_POST['writer'];
                            $shortdesc=$_POST['shortdesc'];
                            $longdesc=$_POST['longdesc'];
                            $date=$_POST['date'];

$sql_update1="UPDATE `tbl_news` SET `title`=:name, `modir_name`=:modir, `tell`=:tell, `mobile`=:mobile, `adres`=:adres, `tarikh_tasis`=:tasis, `tarikh_ezdevaj`=:ezdevaj WHERE `id`='".$_GET['id']."'";
    $result_update1=$connect->prepare($sql_update1);
    $result_update1->bindParam(':name',$name);
    $result_update1->bindParam(':modir',$modir);
    $result_update1->bindParam(':tell',$tell);
    $result_update1->bindParam(':mobile',$mobile);
    $result_update1->bindParam(':adres',$adres);
    $result_update1->bindParam(':tasis',$tasis);
    $result_update1->bindParam(':ezdevaj',$ezdevaj);
    $res=$result_update1->execute();

if($res>0)
die('ok');
else
die('error');
}

?>

by each condition it does upload, delete and insert. but it doesn't upload a file....