PHP won't interpret in Apache+Perl+PHP

Hi, I am stumped on how to make mod_perl and mod_php to coexist peacefully. I have rebuilt my Apache server according to instructions that ought to work (http://scoop.kuro5hin.org/story/2001/2/20/32827/4113), and the server reports that said modules are in place. The top-level of the site is pure Perl, and I have Aliases and Locations that refer to sub-pages that contain .php files. But instead of interpreting the .php files and sending back the results, the web server simply sends back the raw .php files, with the MIME type of application/x-httpd-php. So it looks like the PHP module's content handler is never getting hit, or it's getting hit and failing. I suspect that there is some magic incantation for my httpd.conf, but I've tried everything I can think of. Pointers to any trails to follow would be most appreciated! Many thanks, John