I'm trying to include a navigation menu into my website using PHP. I have two files, test.html and menu.php

The code for test.html is simply:

HTML Code:
    <?php include ("menu.php"); ?>
while the code for menu.php is:

   <a id="navLink" href="aboutus.html"> About Us </a>
When I open test.html in Internet Exlporer, the link is not displaying. I've tried including the complete path in the include() call, and also trying echo in front of the link link in the php file. Nothing I can think of works. Can anyone tell me what I'm doing wrong?