Leech stopped on particular feeds

Hello,

I've mentioned that leech has been stopped importing data on one feed and give nothing during manual feed update.
While trying to edit that Leech it gave me
Error while checking URL: 404, HTTP/1.1 404 Not Found
on checking rss url. http://designcollector.ru/rss.xml
That's strange cos the url is valid and accessible.
I'm thinking of cache, cos once that feed was down... also maybe a slow response, but that was checked twice.
I know that it's a too personal issue, but anyway Error 404 confused me.

Any comments on this?