无法打开流:没有此类文件或目录,但目录为true

I have a project file, and is simple stucture

home/index.php
     folder_1/file1.php
     folder_2/file2.php

if in file1.php i use "require('../index.php');" and it's work, but why i can't use a same sytax at file2.php?

it's a error :

[01-Feb-2017 03:02:58 UTC] PHP Warning:  require(../index.php): failed to open stream: No such file or directory in /home/lingga/public_html/folder_1/file1.php on line 2
[01-Feb-2017 03:02:58 UTC] PHP Fatal error:  require(): Failed opening required '../index.php' (include_path='.:/opt/alt/php56/usr/share/pear:/opt/alt/php56/usr/share/php') in /home/lingga/public_html/administrator/php/config/aplication-pack.php on line 2