hidden field value lost after postback
<p>I have two hidden controls:</p>

<pre><code>&lt;asp:HiddenField runat="server" id="pageHeader" /&gt;
&lt;asp:HiddenField runat="server" id="pageInformation" /&gt;
</code></pre>

<p>I am calling following function from master page:</p>

<pre><code>show_tip(this, document.getElementById('ctl00_pageInformation').value, document.getElementById('ctl00_pageHeader').value);
</code></pre>

<p>and i am passing values in hidden field on .cs page in page load as follows:</p>

<pre><code> string message = Request.Form["pageInformation"];
 if (string.IsNullOrEmpty(message))
 {
      ((HiddenField)Master.FindControl("pageHeader")).Value = pageHeading;
      ((HiddenField)Master.FindControl("pageInformation")).Value = pageInformation;
 }
</code></pre>

<p>This is working fine, but on page <strong>POSTBACK</strong>, hidden fields lose their value. How can I retain the values after postback?</p>
