title: Incomprehension in asp.net
body: <p>I want when I click button my textbox1 must change, but textbox3 not
  Why does not it <strong>work</strong>?</p>
  
  <pre><code>        protected void Page_Load(object sender, EventArgs e)
          {
              TextBox3.Text = DateTime.Now.ToLongTimeString();
          }
  
          protected void Button1_Click(object sender, EventArgs e)
          {
              TextBox1.Text = DateTime.Now.ToLongTimeString();
          }
  
  &lt;asp:ScriptManager ID="ScriptManager1" runat="server"&gt;
          &lt;/asp:ScriptManager&gt;
  
          &lt;asp:UpdatePanel ID="UpdatePanel1" runat="server"&gt;
              &lt;ContentTemplate&gt;
            &lt;asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button"/&gt;
            &lt;asp:TextBox ID="TextBox1" runat="server"&gt;&lt;/asp:TextBox&gt;  
               &lt;/ContentTemplate&gt;
      &lt;br /&gt;
  &lt;asp:TextBox ID="TextBox3" runat="server"&gt;&lt;/asp:TextBox&gt;
          &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>When I Click <strong>Button1</strong> my <strong>TextBox3</strong> changes
  <strong>Why</strong>?</p>