I'm trying to book PHL-AMS, FCO-PHL via the airline website. First I check the availability and fares, using round trips, to verify they fly on the dates I want between those city pairs, and once I've found the flights I want for each leg, I go back to the main page, select "Multi City" and plug in the cities and dates. Every single time it comes up "No flights available on the dates selected" - anybody know why, or how to work around this?