[support] Installation issue on OpenBSD 4.6

I've installed PHP 5 and MySQL 5 per the documented requirements. I have the Drupal 6.14 files in the Apache DOCROOT as instructed. I've created the database and started mysqld. When I get into the Drupal installation script, after "Choose language" and "Verify requirements," in "Set up database," I'm getting this message:

Your web server does not appear to support any common database types

I'm hosting my site on a local server, NATing port 80 traffic on my firewall to a private IP (and of course I can hit the installation script as well as index.html from a browser on another local machine.)

What am I missing?

Thanks.