404. That’s an error.
The requested URL /add?feedurl=http%3A%2F%2Ftickets.cheaptickets.nl%2Fkaartjes%2Frss_feed.buy%3Flink_title%3DNew%2520Tickets%2520-%2520Netherlands%26s_buy%3Dyes%26s_coco%3Dnl%26s_recent%3Dyes
was not found on this server. That’s all we know.