I've had the EXACT same issue with NW the last 2 times they were the cheapest. I have a suffix in my name, which is on my onepass account info, and my CC. I know how to book it just fine on CO.com, but NW couldn't even manually process the ticket over the phone! lol. After multiple transfers and failures for even their supervisors to be able to sell me a ticket.. I went to Co.com, paid $150 more (it was a route CO doesn't normally compete on, which is the only reason i went to NWA.com to begin with!), and the ticket went through just fine. NWA.com has serious name/address matchup issues with suffices.