title: Google charts trendline not showing
body: <p>I have a Google chart line chart that I want to show a trendline on, but it doesn't show up.</p>
  
  <p>The data is fetched from a database and the javascript is generated by PHP but the resulting javascript looks like this:</p>
  
  <pre><code>&lt;script type="text/javascript" src="https://www.google.com/jsapi"&gt;&lt;/script&gt;
  &lt;script type="text/javascript"&gt;
  
  // Load the Visualization API and the piechart package.
  google.load('visualization', '1.0', {'packages':['corechart']});
  
  // Set a callback to run when the Google Visualization API is loaded.
  google.setOnLoadCallback(drawChart);
  
  // Callback that creates and populates a data table, 
  // instantiates the pie chart, passes in the data and
  // draws it.
  function drawChart() {
      var dataS = new google.visualization.DataTable();
      dataS.addColumn('string', 'Dag');
      dataS.addColumn('number', 'Poäng');
      dataS.addRows([
          ['1', 32],
          ['2', 37],
          ['3', 37],
          ['4', 40],
          ['5', 31],
          ['6', 38],
          ['7', 28],
          ['8', 34],
          ['9', 41],
          ['10', 41],
      ]);
  
      var optionsS = {
        title: '',
        legend: 'none',
        hAxis: {title: 'Serie'},
        vAxis: {title: 'Poäng'},
        pointSize: 4,
        trendlines: { 0: {} }
      };
  
      // Instantiate and draw our chart, passing in some options.
      var chart = new google.visualization.LineChart(document.getElementById('chart_div_series'));
      chart.draw(dataS, optionsS);
  }
  &lt;/script&gt;
  </code></pre>
  
  <p>The script is mainly copypaste from the Google charts example. The chart works fine, except for the trend line not showing up. Any ideas why?</p>