Bien, revisando rápidamente el manual surge esto:
http://www.php.net/manual/en/filesys...llow-url-fopen Cita: allow_url_fopen boolean
This option enables the URL-aware fopen wrappers that enable accessing URL object like files. Default wrappers are provided for the access of remote files using the ftp or http protocol, some extensions like zlib may register additional wrappers.
Note:
This setting can only be set in php.ini due to security reasons.
Supongo que esa será la razón de por qué no funciona, es una pena.