google maps api MARKETS php

I want to place the markers on the map with the information stored in my MYSQL db. In the file "index.php" I have the following piece of code that works well with an XML file:

// Change this depending on the name of your PHP or XML file
            downloadUrl('mapmarkers2.xml', function(data) {
                var xml = data.responseXML;
                var markers = xml.documentElement.getElementsByTagName('marker');
                Array.prototype.forEach.call(markers, function(markerElem) {
                    var name = markerElem.getAttribute('name');
                    var address = markerElem.getAttribute('address');
                    var type = markerElem.getAttribute('type');
                    var point = new google.maps.LatLng(
                        parseFloat(markerElem.getAttribute('lat')),
                        parseFloat(markerElem.getAttribute('lng')));

                    var infowincontent = document.createElement('div');
                    var strong = document.createElement('strong');
                    strong.textContent = name
                    infowincontent.appendChild(strong);
                    infowincontent.appendChild(document.createElement('br'));

                    var text = document.createElement('text');
                    text.textContent = address
                    infowincontent.appendChild(text);
                    var icon = customLabel[""] || {};
                    var marker = new google.maps.Marker({
                        map: map,
                        position: point,
                        label: icon.label
                    });
                    marker.addListener('click', function() {
                        infoWindow.setContent(infowincontent);
                        infoWindow.open(map, marker);
                    });
                });
            });

and the file "mapmarkers2.xml":

<markers>
<marker id="1" name="Billy Kwong" address="1/28 Macleay Street, Elizabeth Bay, NSW" lat="-33.869843" lng="-151.225769" type="restaurant"/>
<marker id="2" name="Love.Fish" address="580 Darling Street, Rozelle, NSW" lat="-33.861034" lng="151.171936" type="restaurant"/>
<marker id="3" name="Young Henrys" address="76 Wilford Street, Newtown, NSW" lat="-33.898113" lng="151.174469" type="bar"/>
<marker id="4" name="Hunter Gatherer" address="Greenwood Plaza, 36 Blue St, North Sydney NSW" lat="-33.840282" lng="151.207474" type="bar"/>
<marker id="5" name="The Potting Shed" address="7A, 2 Huntley Street, Alexandria, NSW" lat="-33.910751" lng="151.194168" type="bar"/>
<marker id="6" name="Nomad" address="16 Foster Street, Surry Hills, NSW" lat="-33.879917" lng="151.210449" type="bar"/>
<marker id="7" name="Three Blue Ducks" address="43 Macpherson Street, Bronte, NSW" lat="-33.906357" lng="151.263763" type="restaurant"/>
<marker id="8" name="Single Origin Roasters" address="60-64 Reservoir Street, Surry Hills, NSW" lat="-33.881123" lng="151.209656" type="restaurant"/>
<marker id="9" name="Red Lantern" address="60 Riley Street, Darlinghurst, NSW" lat="-33.874737" lng="151.215530" type="restaurant"/>
</markers>

This works well:

Now the problem, when I change the file "mapmarkers2.xml" to "mapmarkers2.xml", both in the code and in the file and replacement code (as the google documentation says DOCUMENTATION )

I replace the content of the .xml and change the name to .php for the following:

<?php
require("phpsqlajax_dbinfo.php");

function parseToXML($htmlStr)
{
$xmlStr=str_replace('<','&lt;',$htmlStr);
$xmlStr=str_replace('>','&gt;',$xmlStr);
$xmlStr=str_replace('"','&quot;',$xmlStr);
$xmlStr=str_replace("'",'&#39;',$xmlStr);
$xmlStr=str_replace("&",'&amp;',$xmlStr);
return $xmlStr;
}

// Opens a connection to a MySQL server
$connection=mysql_connect ('localhost', $username, $password);
if (!$connection) {
  die('Not connected : ' . mysql_error());
}

// Set the active MySQL database
$db_selected = mysql_select_db($database, $connection);
if (!$db_selected) {
  die ('Can\'t use db : ' . mysql_error());
}

// Select all the rows in the markers table
$query = "SELECT * FROM markers WHERE 1";
$result = mysql_query($query);
if (!$result) {
  die('Invalid query: ' . mysql_error());
}

header("Content-type: text/xml");

// Start XML file, echo parent node
echo '<markers>';

// Iterate through the rows, printing XML nodes for each
while ($row = @mysql_fetch_assoc($result)){
  // Add to XML document node
  echo '<marker ';
  echo 'name="' . parseToXML($row['name']) . '" ';
  echo 'address="' . parseToXML($row['address']) . '" ';
  echo 'lat="' . $row['lat'] . '" ';
  echo 'lng="' . $row['lng'] . '" ';
  echo 'type="' . $row['type'] . '" ';
  echo '/>';
}

// End XML file
echo '</markers>';

?> 

I clarify that the folder "phpsqlajax_dbinfo.php" is with the exact data:

<?php
$username="***";
$password="**";
$database="**";
?>

And the tables in the database are created exactly as the documentation says. But the result is this:

He does not show me any marker