PHP not interpreted.

[redmyrlin]

I originally had Apache 1.3.27 running OK with mod_php4.  I decided to 
add SSL capability so uninstalled apache using "pkg_delete -f ".  I then 
used "make install" in the ports tree to install 
apache+mod_ssl-1.3.27+2.8.14.

Everything seemed to go OK and my plain html files display correctly, 
both on "http" and "https".  However when I point my browser at a  .php 
page I get a text listing of the code and not the interpreted html 
page.  I'm sure I've broken or misconfigured something and just need 
someone to point out my stupidity.

Please, what have I done wrong and how can I correct it?

TIA
Graeme