I'm having trouble booking a ticket from CLT to SVO, via IAD. I'd like to take advantage of Aeroflot's cheaper ticket from IAD to SVO, but for some reason, all the online ticketing sites refuse to combine a US carrier with Aeroflot.

Does anyone know why this is happening?

Should I just book two separate tickets (CLT to IAD; and IAD to SVO)? If I book separate tickets, do I have to claim my bags at IAD and then check them in again at IAD?

thanks for any help you can provide. I really appreciate it.