update Panel is not working properly in asp.net 3.5
<p>I am using update panel if I remove it then Master Page error acre(display) which as followed
The Page Contain markup that is not valid when attachment to a Master page.
 Correct The Problem in Code View
if I select the Code view
then 
following part of would be high lighted</p>

<pre><code>&lt;asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server"&gt;
&lt;link href="Bin/StyleSheet.css" rel="stylesheet" type="text/css" /&gt;
&lt;style type="text/css"&gt;
    .tdStyle
    {
        width: 33.33%;
    }
    .tdDMLLeft
    {
        width: 20%;
    }
    .tdDMLRight
    {
        width: 30%;
    }
    .gridLength
    {
        white-space: nowrap;
    }
&lt;/style&gt;

&lt;script type="text/javascript"&gt;
    function btCheck()
    {
        var btResult;
        btResult = confirm("Do You Confirm ?");
        if(btResult ==true)
            return true;
        else if(btResult ==false)
            return false;
    }
&lt;/script&gt;
&lt;/asp:Content&gt;
</code></pre>
