Originally Posted by
zhlobsky
cross-check your availability/inventory results on EF and KVS...
Are you connecting? Inventory in a fare bucket aaa-bbb and bbb-ccc doesn't mean availability aaa-bbb-ccc: married segment availability may prevent this.
Search for entire itineraries on ITA Software then go to delta.com to book. Very seldom (although I can't say never) does this fail.