problem med sessions

faar den her fejl naar jeg bruger sessions. min host www.unoeuro.com

Warning: session_start(): Cannot send session cache limiter - headers already sent (output started at /var/www/keep-gaming.com/ladder/shop.php:15) in /var/www/keep-gaming.com/ladder/shop.php on line 24

nogen der ved hvorfor det sker bruger bare

session_start();

$_SESSION["censur"] = $censur->censur();