Connecting Google Chart(Gauge chart) to MySQL database

I am working on Gauge visualization using google chart library,PHP,MySQL (Gauge chart with Real time Updation) I wrote the code in PHP and connecting to MySQL database to use elapsed table in database for generating Gauge chart. It works well for Pie-chart,bar-chart, column chart, Line-chart but it's not working with Gauge-chart. Can any one please help with this problem. Here My code is as follows:

Gauge.php

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

// Set a callback to run when the Google Visualization API is loaded.

google.charts.setOnLoadCallback(drawChart);

function drawChart() {
    var data;

    var options = {
        width: 400,
        height: 120,
        redFrom: 90,
        redTo: 100,
        yellowFrom: 75,
        yellowTo: 90,
        minorTicks: 5
    };
    var chart = new google.visualization.Gauge(document.getElementById('image_div'));
    function refreshData() {
        var json = $.ajax({url:'imagebar.php',dataType: 'json', async: false}).responseText;
        data = google.visualization.arrayToDataTable(json);

        chart.draw(data, options);
    }
    refreshData();
    setInterval(refreshData, 1000);
}

and My imagebar.php code is as follows: imagebar.php

$sql = "SELECT wonum, DATEDIFF(dt_on,dt_off) AS elapsedday from elapsed;";
echo $wonum, $elapsedaday;

$query = mysql_query($sql);
while($result = mysql_fetch_array($query))
{
    $MDHAdata[] = array($result['wonum'],(int)$result['elapsedday']);
}