Have you edited httpd.conf to accept the file-ending you're using, and throw it to the parser?
This needs to be specified:
AddType application/x-httpd-php .phtml .inc .php
AddType application/x-httpd-php-source .phps
and this:
<IfModule mod_dir.c>
DirectoryIndex index.php index.html index.htm index.shtml default.htm index.wml
</IfModule>
knutm