我想用PHP更改上传的图像

php block

    if ($_FILES['fileField']['tmp_name'] != "") {
        $newname = "image01.jpg";
        move_uploaded_file($_FILES['fileField']['tmp_name'], "_include/img/slider-images/$newname");
    }
    header("location: manage.php"); 
    exit();

}

html block

            <input type="file" name="fileField" id="fileField" />

this code doesn΄t work. i checked permissions and everything seems fine. any ideas?