title: Custom Dimension value alway showing up as not set
body: <p>I am trying to create custom dimension using GTM, dataLayer and GoogleAnalytics.</p>
  
  <p>In GTM, created a user defined variable.
  <a href="https://i.stack.imgur.com/8dyf5.png" rel="nofollow noreferrer">UserVariable</a></p>
  
  <p>I have something like this in my html page</p>
  
  <pre><code>    &lt;script&gt;
  function addCategory(){
    dataLayer.push({
        'category' : 'drama'
    }
  );
  }
  &lt;/script&gt;
  &lt;/head&gt;
  
  &lt;body onload="addCategory()"&gt;
  </code></pre>
  
  <p>In Google analytics created custom dimension</p>
  
  <p><a href="https://i.stack.imgur.com/7v1tT.png" rel="nofollow noreferrer">Custom Dimension</a></p>
  
  <p>In the GTM in tags section, associated the dimension that was created with the user defined variable.</p>
  
  <pre><code>Index - 2
  Dimension Value - {{category}}
  </code></pre>
  
  <p>In the Preview and Debug mode i can see that value in the Variables section.</p>
  
  <p>category Data Layer Variable string 'drama'</p>
  
  <p>But in Google Analytics i always seeing that value as (not set).</p>
  
  <p>What have i done wrong</p>