PHP show_source无法在我的服务器上运行（Altervista）

I am trying to display the PHP source of a file inside a page. I am using show_source function in this way:

<?php
$nomefile = $_REQUEST['nome'];
show_source($nomefile);
?>

When I try this code on my local PC (using USBWebserver v8.6), it works smoothly, displaying the PHP code of the page. But when I try it on my remote webserver (Altervista), I only get an empty page.

I even try to substitute variable $nomefile with name "visite.php", which is the name of a file residing in the same folder, but still I get no result? I try with echo show_source(...), but no result again.

Is there an error in my code? Or maybe show_source is not compatible with all version of PHP? Is there any easy alternative?

Thanks a lot Giancarlo Perlo - Italy