I've been getting the same message for the last 3 weeks-- ever since they launched the 3-tier system. I thought it was whenever I attempt to book a multiple-city itinerary instead of a simple round-trip. I wonder, though, whether I was attempting to select a partner segment. Others have reported the same error when they select 'multiple dates' instead of 'exact dates'. I worked with tech support: at first they gave me a reason for the error that had nothing to do with what I was attempting, showing that they completely misunderstood the nature of my problem. After I pointed this out, the guy got snippy and told me that if I'm having a problem then I'll need to book the award ticket by phone.
