Originally Posted by
Deathray
The mismatch is usually because matrix usually checks availability on a segment basis (especially if you're specifying a multi city booking or very specific routing codes).
Matrix tends to check availability on a
slice basis (matrix/qpx terminology for the individual search components). Availability accuracy on a multi-city therefore is highest if you minimize the number of O&D pairs in the search.
Unnecessarily searching by segment on a multi-city is one of the more common causes of unbookable itineraries people send to me. Matrix has many other issues with availability of course, not saying that is necessarily the issue here.