i try to geht the data from a xml file and i have troubles to get data, for example, how can i get the caaml:locRef value or the caaml:beginPosition value?

here is the code so far:

/* a big thank you to helderdarocha */
/* – he already helped me yesterday with a part of this code */ 

$doc = new DOMDocument();
    $doc->load('xml/test.xml');

    $xpath = new DOMXpath($doc);
    $xpath->registerNamespace("caaml", "http://caaml.org/Schemas/V5.0/Profiles/BulletinEAWS");

    if ($doc->schemaValidate('http://caaml.org/Schemas/V5.0/Profiles/BulletinEAWS/CAAMLv5_BulletinEAWS.xsd')) {

        foreach ($xpath->query('//caaml:DangerRating') as $key) {
            echo $key->nodeValue;
            print_r($key);
        }

    } 

and here ist the print_r from $key

DOMElement Object ( [tagName] => caaml:DangerRating [schemaTypeInfo] => [nodeName] => caaml:DangerRating [nodeValue] => 2014-03-03+01:00 2 [nodeType] => 1 [parentNode] => (object value omitted) [childNodes] => (object value omitted) [firstChild] => (object value omitted) [lastChild] => (object value omitted) [previousSibling] => (object value omitted) [nextSibling] => (object value omitted) [attributes] => (object value omitted) [ownerDocument] => (object value omitted) [namespaceURI] => http://caaml.org/Schemas/V5.0/Profiles/BulletinEAWS [prefix] => caaml [localName] => DangerRating [baseURI] => /Applications/MAMP/htdocs/lola/xml/test.xml [textContent] => 2014-03-03+01:00 2 ) 2014-03-04+01:00 2 

and here a part of the xml

 <caaml:DangerRating>
      <caaml:locRef xlink:href="AT7R1"/>
      <caaml:validTime>
        <caaml:TimePeriod>
          <caaml:beginPosition>2014-03-06T00:00:00+01:00</caaml:beginPosition>
          <caaml:endPosition>2014-03-06T11:59:59+01:00</caaml:endPosition>
        </caaml:TimePeriod>
      </caaml:validTime>
      <caaml:validElevation>
        <caaml:ElevationRange uom="m">
          <caaml:beginPosition>2200</caaml:beginPosition>
        </caaml:ElevationRange>
      </caaml:validElevation>
      <caaml:mainValue>2</caaml:mainValue>
    </caaml:DangerRating>
    <caaml:DangerRating>
      <caaml:locRef xlink:href="AT7R1"/>
      <caaml:validTime>
        <caaml:TimePeriod>

thanks!