FormatOutput nie działa Opcje

[gcdreak]

Witam! Mam problem z właściwością formatOutput clasy domDocument;
Mój kod wygląda tak:

[PHP] pobierz, plaintext 
    $str ="
<datas>
      <books> 
        <book>
            <id>1</id>
            <title>PHP Undercover</title>     
            <author>Wiwit Siswoutomo</author>
        </book>
        <book>
              <id>2</id>
              <title>PHP Enterprise</title>     
              <author>Wiwit Siswoutomo</author>
        </book>
    </books>
</datas>
";
 
    $dom = new DOMDocument();
    $dom->loadXML($str);
 
    //    $dom settings
    $dom->formatOutput = true;
    $dom->preserveWhiteSpace = false;
 
    //    get root element(datas)
    $root = $dom->documentElement;
 
    //create new book's nodes
    $id = $dom->createElement('id');
    $id->appendChild($dom->createTextNode('3'));
 
    $title = $dom->createElement('title');
    $title->appendChild($dom->createTextNode('Kamienie na szaniec'));
 
    $author = $dom->createElement('author');
    $author->appendChild($dom->createTextNode('Aleksander Kaminski'));
 
    // create new book node
    $newBook = $dom->createElement('book');
    //    append childs to new book
    $newBook->appendChild($id);
    $newBook->appendChild($title);
    $newBook->appendChild($author);
 
    //    get parent for book
    $books = $dom->getElementsByTagName('books')->item(0);
 
    //    add new book to $dom
    $books->appendChild($newBook);
 
    // display
    echo '<xmp>'.$dom->saveXML().'</xmp>';
[PHP] pobierz, plaintext 

Niestety nowy węzeł nie jest odpowiednio sformatowany i jest wyświetlany w jednej linii:

Kod

   <pre id="line1"><span class="pi"><?xml version="1.0"?></span>
<<span class="start-tag">datas</span>>
       <<span class="start-tag">books</span>>
        <<span class="start-tag">book</span>>
            <<span class="start-tag">id</span>>1</<span class="end-tag">id</span>>
            <<span class="start-tag">title</span>>PHP Undercover</<span class="end-tag">title</span>>    
            <<span class="start-tag">author</span>>Wiwit Siswoutomo</<span class="end-tag">author</span>>
        </<span class="end-tag">book</span>>
         <<span class="start-tag">book</span>>
</pre><pre id="line10">              <<span class="start-tag">id</span>>2</<span class="end-tag">id</span>>
              <<span class="start-tag">title</span>>PHP Enterprise</<span class="end-tag">title</span>>    
              <<span class="start-tag">author</span>>Wiwit Siswoutomo</<span class="end-tag">author</span>>
         </<span class="end-tag">book</span>>
    <<span class="start-tag">book</span>><<span class="start-tag">id</span>>3</<span class="end-tag">id</span>><<span class="start-tag">title</span>>Kamienie na szaniec</<span class="end-tag">title</span>><<span class="start-tag">author</span>>Aleksander Kaminski</<span class="end-tag">author</span>></<span class="end-tag">book</span>></<span class="end-tag">books</span>>
</<span class="end-tag">datas</span>>
</pre>

Co może być tego przyczyną?