I can not get <?= to work on one of my servers, any ideas why ?

[eluser]tobias eriksson[/eluser]
Typically we use <?php echo $variabel; ?>when we want to use php to do something,
but as you also know it is possible to use <?=$variable?>
and that worked fine on the server I use for my company (webhosting web10.se)
but when I tried to integrate my system into the customers webserver it wouldn't translate that at all.
Anyone who knows why ?
What is missing to get that to work

/Tobias