ayuda con este error

[gutibs]

Buen dia foreros, estoy tratando de geocodificar con las api de google maps los datos de una tabla, pero me tira el siguiente error, y lo mio la verdad que no es el xml....

Warning: simplexml_load_file() [function.simplexml-load-file]: php_network_getaddresses: getaddrinfo failed: Host desconocido. in

este es el codigo:

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

define("MAPS_HOST", "maps.google.com");
define("KEY", "ABQIA");

// 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 markers3 WHERE 1";
$result = mysql_query($query);
if (!$result) {
die("Invalid query: " . mysql_error());
}

// Initialize delay in geocode speed
$delay = 0;
$base_url = "http://" . MAPS_HOST . "/maps/geo?output=xml" . "&key=" . KEY."&oe=utf-8";

// Iterate through the rows, geocoding each address
while ($row = @mysql_fetch_assoc($result)) {
$geocode_pending = true;

while ($geocode_pending) {
$address = $row["address"];
$id = $row["id"];
$request_url = $base_url . "&q=" . urlencode($address);
$xml = simplexml_load_file($request_url) or die("url not loading");

$status = $xml->Response->Status->code;
if (strcmp($status, "200") == 0) {
// Successful geocode
$geocode_pending = false;
$coordinates = $xml->Response->Placemark->Point->coordinates;
$coordinatesSplit = split(",", $coordinates);
// Format: Longitude, Latitude, Altitude
$lat = $coordinatesSplit[1];
$lng = $coordinatesSplit[0];

$query = sprintf("UPDATE markers3 " .
" SET lat = '%s', lng = '%s' " .
" WHERE id = '%s' LIMIT 1;",
mysql_real_escape_string($lat),
mysql_real_escape_string($lng),
mysql_real_escape_string($id));
$update_result = mysql_query($query);
if (!$update_result) {
die("Invalid query: " . mysql_error());
}
} else if (strcmp($status, "620") == 0) {
// sent geocodes too fast
$delay += 100000;
} else {
// failure to geocode
$geocode_pending = false;
echo "Address " . $address . " failed to geocoded. ";
echo "Received status " . $status . "
\n";
}
usleep($delay);
}
}
?>


Si alguien me puede dar una mano se los voy a agradecer muchisimo por que es para un trabajo que me piden.