Following code shows error Uncaught TypeError: Cannot set property 'className' of null

  <style>

      .deactive { height:250px; }

      .active { height:150px; }

  </style>

  <script>

      function click(div) {

          document.getElementById('div').className  = 'active';

      }

  </script>

  <a href=# onclick=click(Division);>

      <div id=Division class=deactive>

          <!--Division contents-->

      </div>

  </a>

i am trying pass id of division to js function by on click event of anchor tag.. and i want to change the class name of the division,
help me to identify the error..