To get this to work you need to edit your
httpd.conf file.
Find the line that looks similar to this:AddType application/x-httpd-php .php
and change it to look like this:AddType application/x-httpd-php .php .htm .html
and all should be fine
If the server is shared :
Instead it can be put in .htaccess for the site.
AddType application/x-httpd-php .php .htm .html
Please restart httpd service after this