使用Google Chart API PHP和Mysql时出错

I'm trying to display numbers and datetime from sql server in a LineChart. But I'm getting the following error in my html page : "Undefined is not a function"

My html code :

<html>
<head>
<script src="script/jquery-1.11.1.js" type="text/javascript"></script>
<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript">

// Load the Visualization API and the piechart package.
google.load('visualization', '1', {'packages':['corechart']});

// Set a callback to run when the Google Visualization API is loaded.
google.setOnLoadCallback(drawChart);

function drawChart() {
  var jsonData = $.ajax({
      url: "getData.php",
      dataType:"json",
      async: false
      }).responseText;

  // Create our data table out of JSON data loaded from server.
  var data = new google.visualization.DataTable(jsonData);

  // Instantiate and draw our chart, passing in some options.
  var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
  chart.draw(data, {width: 400, height: 240});
}
google.setOnLoadCallback(drawChart);

</script>
</head>
<body>
<div id="chart_div"></div>
</body>
</html>

My php :

<?php
    include("connect.php");

    $rq = " SELECT  dateUpdate, W_3P FROM real_time_measure";
    $result = mysqli_query($link, $rq);
    $table = array();
    $table['cols'] = array(
        array('label' => 'datetime', 'type' => 'datetime'),
        array('label' => 'mesure', 'type' => 'number')
    );

    $rows = array();
    while($r = mysqli_fetch_assoc($result)) {
        $temp = array();
        // each column needs to have data inserted via the $temp array
        $temp[] = array('v' => $r['dateUpdate']);
        $temp[] = array('v' => (float) $r['W_3P']);
        // etc...

        // insert the temp array into $rows
        $rows[] = array('c' => $temp);
    }

    // populate the table with rows of data
    $table['rows'] = $rows;


    // return the JSON data
    $jsonTable = json_encode($table);
    echo $jsonTable;
?>

EDIT This code returns : {"cols":[{"label":"datetime","type":"string"},{"label":"mesure","type":"number"}],"rows":[{"c":[{"v":"2014-04-15 21:35:14"},{"v":12.4}]},{"c":[{"v":"2014-04-15 21:35:14"},{"v":12.4}]},...]}]}

This code comes from other topics in this forum. Does anybody know where this error come from? Thanks for your help, Jordan.

UPDATE

If i change async to true in the drawChart function. The error returned is : "Table has no columns. "

UPDATE II

If I past json data in the vizualisation.LineChart() function it's work. So the issue must be in $.ajax function. ??