It means that the current sources aren't accepting any more requests, and so you need to repeat the search to find new sources.

btw, most people allow 3 downloads per user, so if you request more than two or three files from a user, the extra requests get ignored, or even banned. So, if you tried to download 20 eps from one person, most of those requests will show "need more sources"

The safest thing to do is only download a few files at a time, especially if it looks like they are coming from one source.

If you share the file once you're done, you'll save the next person the same hassle you're getting.