Phusion Passenger (Apache, Sinatra) suddenly not working for a single site on my server

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http://serverfault.com – I've had Phusion Passenger working for a few of my sites for months. Then, today, it stopped working for a single site. I hadn't changed anything (I hadn't even SSH'ed into the server for a week), and everything is set up the way it should for it to work. Plus, it's working fine for other sites! I'm about to pull my hair out trying to find out what's wrong, so I was hoping y'all could help. Passenger is not working on kerricklong.com -- I only get the "It works!" Apache default page. If I look at the headers, it's not even serving the X-Powered-By: Phusion Passenger (mod_rails/mod_rack) heade (HowTos)