wp_schedule_event in a class

This is my (stripped down) plugin, in OOP:

class MyClass {

    public function __construct() {
		// scheduled tasks
		if ( !wp_next_scheduled( 'dailyops' ) ) {
		    wp_schedule_event( time(), 'daily', 'dailyops' );
		}
		add_action( 'dailyops', array($this, 'do_this_daily') );
    }

    function do_this_daily() {
    		// do something every day
    		error_log('daily');
    }
}

Anyway, it’s not working (do_this_daily() is never fired). I tried the same in a non-OOP plugin (not based on a class) and it works flawlessy. How can I make it work here, in a class?