.aspx code errors "Element 'xxxx' is not supported."
<p>I'm getting a bunch of these errors for my image buttons, link buttons, text boxes, and labels.  These errors are in my .aspx code.  Why am I getting so many?</p>

<pre><code>&lt;%@ Page Language="C#" AutoEventWireup="true" CodeFile="frmSearchPersonnel.aspx.cs" Inherits="frmSearchPersonnel" %&gt; 

&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt; 

&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt; 
&lt;head id="Head1" runat="server"&gt; 
    &lt;title&gt;Untitled Page&lt;/title&gt; 
&lt;/head&gt; 
&lt;body&gt; 
    &lt;form id="form1" runat="server"&gt; 
    &lt;div&gt; 

    &lt;div align="center"&gt; 


    &lt;/div&gt; 

    &lt;/div&gt; 
    &lt;asp:Label ID="Label1" runat="server" Text="Search for employee by last name"&gt;&lt;/asp:Label&gt; 
    &lt;asp:TextBox ID="txtSearchName" runat="server"&gt;&lt;/asp:TextBox&gt; 
    &lt;p&gt; 
        &lt;asp:Button ID="btnSearch" runat="server" PostBackUrl="~/frmViewPersonnel.aspx"  
            Text="Search" onclick="btnSearch_Click" /&gt; 
    &lt;/p&gt; 
    &lt;/form&gt; 
&lt;/body&gt; 
&lt;/html&gt;.
</code></pre>

<p>The errors are under Label, TextBox &amp; Button above in blue. The errors state:</p>

<blockquote>
  <p>Validation (): Element 'xxxx' is not supported.</p>
</blockquote>
