(PHP) The include function only includes some parts of the file

I have a problem including a php file. I have searched on the web, and troubleshooted in different ways for three hours, But I can't figure it out on my own.

I have a file called "side9test.php" with this code:

<?php

include "styret/fil-liste.php"; 

?>

The file "fil-liste.php" contains:

<?php
echo "</br>";
echo file_get_contents("filsystem_navn/m_0.txt");

?>

The file "m_0.txt" contains this:

forste mappa

The problem though, When I run "side9test.php", all it gives me is:

</br>

I appreciate all feedback!