Beginner question

I am trying to use PHP on my web site I am developing now. I have installed Apache 2.2 and PHP 5.2. My problem is that I can execute PHP code embedded in my HTML code, but I can't execute the same cose when I put it into a separate .php file that i then call from within the html code. for example: I have a html file with <body> <?php echo "Printing with php"; ?> <?body> and it works fine. When I take out the php code and put it inot a file pp.php, and I call that file with my browser ("localhost/pp.php"), it works, too. But when I change the html code to: <body> <script type="text/javascript" src="pp.php"></script> </body> I get a blank page. this is probably something really stupid, but I have been wrecking my head for days now, and I can't figure it out. anybody has an idea?