ITA matrix searches time out after 60 seconds. So the broader the search is, the lesser acurate the results are. Calendar search is good to get a price range... But then it's better to redo the search with +/- 2 days around your desired travel dates.
Also, if you're looking for specific airlines, try narrowing down your search using advanced routing codes.
You can restrict to a specific alliance for instance (but keep in mind that won't display itineraries with out of alliance partners).
The great power of ITA is its ability of fine tuning searches, and being able to avoid being spammed with 40 h transatlantic itin. with 2 overnight lahovers for $50 less than a direct route. There's a thread somewhere (edit: here
) on this board explaining all the advanced routing stuff... You can alsoclick on the 'Help
' link at the top right of the ITA Matrix webpage, but most of it remains undocumented.