[Opserty]

From php.net:

PHP Code:

// Won't work; looks for a file named 'file.php?foo=1&bar=2' on the
// local filesystem.
include 'file.php?foo=1&bar=2';

// Works.
include 'http://www.example.com/file.php?foo=1&bar=2'; 


So in your case it would be:

PHP Code:

ob_start();
include('http://www.yourdomain.com/index.php?t=index_menu');
$includedphp = ob_get_contents();
ob_end_clean(); 


(Where obviously www.yourdomain.com is the actual domain name of your site.)

Its a bit of a guess but it's worth a try.