php 移动文件失败怎么办

<?php
include("../Include/Conn.php");
include("../Include/Function.php");
include("../Include/Data.php");
$uploadPage="edit_headimage.php";
$dir=$file_upload_root.'HeadImages'; # 上传的文件目录
$err_msg=false;
$err_msg_behind='，请重新<a href="'.$uploadPage.'">上传</a>。';
if (!isset($_FILES['upfile'])) $err_msg='表单不完全'.$err_msg_behind;
else $fileImg=$_FILES['upfile'];
switch($fileImg['Error']){
case 1:
$err_msg='文件超过最大上传限制'.$err_msg_behind;
break;
case 3:
$err_msg='文件上传不完全'.$err_msg_behind;
break;
case 4:
$err_msg='没有选择文件'.$err_msg_behind;
break;
case 2:
$err_msg='文件超过页面最大上传限制'.$err_msg_behind;
break;
case 7:
$err_msg='文件写入失败'.$err_msg_behind;
break;
case 6:
$err_msg='没有临时文件夹'.$err_msg_behind;
break;
case 0:
break;
default:
$err_msg='未知错误'.$err_msg_behind;
}
if (!in_array($fileImg['type'],array('image/jpeg','image/pjpeg','image/png'))) $msg="只允许上传png或jpg图片".$err_msg_behind;
if (!$err_msg){
if (!move_uploaded_file($fileImg['temp_name'],$dir.$fileImg['name'])){
$err_msg='移动文件失败'.$err_msg_behind;
}
}
if ($err_msg) error ($err_msg);
else{
echo '完成';
}
include("../Include/Close.php");
?>

if (!move_uploaded_file($fileImg['temp_name'],$dir.$fileImg['name'])){
$err_msg='移动文件失败'.$err_msg_behind;
}