There was a SharePoint farm not returning search results. The error it returned was
"The search request was unable to connect to the Search Service"
After looking at it, it was a very simple fix. The server wasn't configure to server search queries. A simple ticking of the box in central admin and it fixed the problem. To fix this:
Another thing that could be causing it is the Account used to search might not have the right access needed or the Search services aren't running. Check that
- Office SharePoint Server Search and
- Windows SharePoint Services Search
Should be both running. If you're still having problems, let me know and I'll try to help you out.