XML : PHP XML cant get values

I have a string like this:

  <?xml version="1.0" encoding="utf-8"?>  <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">  <soap:Body>  <GetListItemsResponse xmlns="http://schemas.microsoft.com/sharepoint/soap/">  <GetListItemsResult>  <listitems>  <rs:data>     <z:row ows_MetaInfo='128;#' />  </rs:data>  </listitems>  </GetListItemsResult>  </GetListItemsResponse>  </soap:Body>  </soap:Envelope>    

I would like to get the value 128.

I already tried simplexml_load_string which is empty.

How can I get this attribute?