Same issue, different line. Change line 290 to
Code:
                   'state' => ($order->delivery['country']['id'] != '' ? zen_get_zone_code((int)$order->delivery['country']['id'], (int)$order->delivery['zone_id'], $order->delivery['state']) : zen_get_zone_code((int)$order->billing['country']['id'], (int)$order->billing['zone_id'], $order->billing['state'])),