Why can't display a DateTime object
<pre><code>$date = new DateTime(2011-10-05);
echo $date-&gt;format('Y-m-d H:i:s');
</code></pre>

<p>Running the above code, the page is displayed nothing. Just wondering is there anything wrong on the code and I used the <strong>PHP5 (Version 5.3.0)</strong>.</p>

<p>Can anyone help me? Thanks in advance!</p>

<p><strong>--Update---
After adding quotes, still nothing is displayed.</strong></p>

<pre><code>$date = new DateTime("2011-10-05");
    echo $date-&gt;format('Y-m-d H:i:s');
</code></pre>
