I want to book a multi-city itinerary on Air France, including CDG -> KIX and KIX -> LHR. Air France offers flights for these two pairs and it seems that I would be able to book them separately without problems (although very expensive, of course). However, I can not book them together (for any amount of money). When I search in ITA Matrix, this combination on Air France does not show up (even if the two simple directions appear). When I search the Air France website, I feel a little hope because, on the first page after the search, it indicates indeed many flights in both directions. However, when I select the flights I want, a strange error message tells me "There are no flights available, change your travel dates." (even if she just posted flights available!). Is there any hope of reserving this combination, perhaps through a SkyTeam partner, or does Air France simply refuse this type of flight combination?
By the way, the combination CDG -> KIX and NRT -> CDG seems to be easily reserved.