PHP - Google me detecta el sitemap como HTML

<?php

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

echo "<?xml version='1.0' encoding='UTF-8'?>";

echo "<urlset xmlns='http://www.sitemaps.org/schemas/sitemap/0.9'

        xmlns:news='http://www.google.com/schemas/sitemap-news/0.9'>";

    require 'admin/config.php';

    require 'funciones.php';

    try {

        $conexion = new PDO($bd_config['dbname'], $bd_config['usuario'], $bd_config['password'] );

    } catch (PDOException $e) {

        header ('Location: error.php');

        echo "ERROR: ".$e->getMessage();

        die();

    }

    $hoy = getdate();

    $mes = $hoy['mon'];

    $dia = $hoy['mday'];

    if ($hoy['mon'] < 10) {

        $mes = "0" . $mes;

    }

    if ($hoy['mday'] < 10) {

        $dia = "0" . $dia;

    }

    $fecha_hoy = $hoy['year'] . "-" . $mes . "-" . $dia;

    echo "<url>\n";

      echo "<loc>http://www.laxtore.com/</loc>\n";

      echo "<lastmod>" . $fecha_hoy . "</lastmod>\n";

      echo "<changefreq>daily</changefreq>\n";

      echo "<priority>1</priority>\n";

    echo "</url>\n";

    echo "<url>\n";

      echo "<loc>http://www.laxtore.com/Juegos/Indice-Precios/</loc>\n";

      echo "<lastmod>" . $fecha_hoy . "</lastmod>\n";

      echo "<changefreq>daily</changefreq>\n";

      echo "<priority>1</priority>\n";

    echo "</url>\n";

    echo "<url>\n";

      echo "<loc>http://www.laxtore.com/contacto/</loc>\n";

      echo "<priority>0.8</priority>\n";

    echo "</url>\n";

    echo "<url>\n";

      echo "<loc>http://www.laxtore.com/Juegos/Xbox-One/</loc>\n";

      echo "<lastmod>" . $fecha_hoy . "</lastmod>\n";

      echo "<changefreq>daily</changefreq>\n";

      echo "<priority>1</priority>\n";

    echo "</url>\n";

    $statement = $conexion->prepare("SELECT * FROM retrocompatibles_360 ORDER BY Agregado DESC");

    $statement->execute();

    $ultimo_juego_360 = $statement->fetchAll();

    echo "<url>\n";

      echo "<loc>http://www.laxtore.com/Juegos/Xbox-360/</loc>\n";

      echo "<lastmod>" . substr($ultimo_juego_360[0]['Agregado'],0,10) . "</lastmod>\n";

      echo "<changefreq>daily</changefreq>\n";

      echo "<priority>1</priority>\n";

    echo "</url>\n";

    $statement = $conexion->prepare("SELECT * FROM retrocompatibles_360 WHERE retro = 1 ORDER BY Agregado DESC");

    $statement->execute();

    $ultimo_juego_360_retro = $statement->fetchAll();

    echo "<url>\n";

      echo "<loc>http://www.laxtore.com/Juegos/Xbox-One/retrocompatibles/</loc>\n";

      echo "<lastmod>" . substr($ultimo_juego_360_retro[0]['Agregado'],0,10) . "</lastmod>\n";

      echo "<changefreq>monthly</changefreq>\n";

      echo "<priority>1</priority>\n";

    echo "</url>\n";

    echo "<url>\n";

      echo "<loc>http://www.laxtore.com/Juegos/Deals-With-Gold/</loc>\n";

      echo "<changefreq>weekly</changefreq>\n";

      echo "<priority>1</priority>\n";

    echo "</url>\n";

    $statement = $conexion->prepare("SELECT * FROM art ORDER BY fecha_publicacion");

    $statement->execute();

    $articulos = $statement->fetchAll();

    foreach ($articulos as $articulo) {

        echo "<url>\n";

          echo "<loc>http://www.laXtore.com/noticia/" . $articulo['ID'] . "/" . limpia_url($articulo['titulo']) . "/</loc>\n";

          echo "<news:news>\n";

            echo "<news:publication>\n";

              echo "<news:name>LaXtore</news:name>\n";

              echo "<news:language>es</news:language>\n";

            echo "</news:publication>\n";

            echo "<news:genres>Tecnología, Xbox One, videojuegos, videogames</news:genres>\n";

            echo "<news:publication_date>" . substr($articulo['fecha_publicacion'],0,10) . "</news:publication_date>\n";

            echo "<news:title>" . str_replace("&","and",$articulo['titulo']) . "</news:title>\n";

            echo "<news:keywords>" . str_replace(",", ";",str_replace("&","and",$articulo['etiquetas'])) . "</news:keywords>\n";

          echo "</news:news>\n";

        echo "</url>\n";

    }

    $statement = $conexion->prepare("SELECT * FROM info_XboxOne ORDER BY agregado DESC");

    $statement->execute();

    while ($xbox_individual = $statement->fetch()) {

        echo "<url>\n";

          echo "<loc>http://www.laxtore.com/Juegos/Xbox-One/" . $xbox_individual['id'] . "/" . limpia_url($xbox_individual['Juego']) . "/</loc>\n";

          echo "<lastmod>" . substr($xbox_individual['agregado'],0,10) . "</lastmod>\n";

          echo "<priority>0.8</priority>\n";

        echo "</url>\n";

    }

echo "</urlset>\n";

?>

RewriteRule ^sitemap\.xml$ sitemap.php [L]

Sitemap: http://www.laxtore.com/sitemap.xml