Img-responsive is unresponsive!

I am trying to use bootstrap as much as possible for my tribute page. I have added the img-responsive class to my image but it doesn’t resize when I make my page smaller. I have also tried img-circle and img-rounded but they don’t work either. However, strangely, img-thumbnail does work. Here is the complete html for my page.

<link href="" rel="stylesheet">

<div class="container-fluid">
  <div class="row">
    <div id="container" class="col-xs-12">
    <header class="text-center text-primary">
      <h1>Hack Wanger</h1>
      <h2>A Tribute</h2>
      <img class="img-responsive center-block" src="" alt="Hack Wanger portrait"/>
      <figcaption>Hack Wanger with his trademark guitar god pose</figcaption>
    <h3>Here are a few things you didn't know about Hack:</h3>
      <li>His real name is David Loader</li>
      <li>His TV show, "Guitar Gods and Masterpieces" has been broadcasting on Channel 31 since 2010 and has run for 300 episodes</li>
      <li>He hosts the only guitar TV show in the world</li>
      <li>He had no background in film or TV befire starting the show</li>
      <p>I have been passionate about music, and playing the guitar, for as long as I can remember...</p>
      <footer>Hank Wanger in an interview with <cite>Pearl HQ</cite></footer>
      <p>Find out about Hack's campaign to raise money for prostate cancer and depression through <a href="">The Epic Guitar Solo Challenge.</a></p>

Any help appreciated:

See this thread and see if that’s the case