note 15813 added to function.ob-start

I'm having trouble trying to use a class method as a callback function I tried several variations with no luck ob_start('$this->callback'); //not sure why this doesn't work ob_start('$this->callback()'); // missing first arg error ob_start($this->callback); // sustitutes non-existant obj var ob_start("$this->callback"); // sustitutes non-existant obj var any ideas ? -- http://www.php.net/manual/en/function.ob-start.php http://master.php.net/manage/user-notes.php?action=edit+15813 http://master.php.net/manage/user-notes.php?action=delete+15813 http://master.php.net/manage/user-notes.php?action=reject+15813