Display ticket remaining time
<p>I am programming small page and I want to display expiration time of authentication ticket. I mean not the end, but remaining time. Current code is follows:</p>

<pre><code>    DateTime cas = (DateTime)ticket.Expiration.Date;
    DateTime cas1 = DateTime.Now;
    DateTime cas2 = cas1.Subtract(cas);
</code></pre>

<p>However, VS says "Cannot implicitly convert system.timespan into system datetime".
 Pls help. Thanks a lot.</p>
