I've learning ASP.NET using c# at present. I've got an example of using code behind but its not working can anyone point out why its not working?

myCodeBehind.cs:

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

public class myCodeBehind: Page {
protected Label lblMessage;
protected void Button_Click(Object sender , EventArgs e) {
lblMessage.Text="Hello World!!";
}
}

Presentation.aspx

<%@ Page codebehind="myCodeBehind.cs" Inherits="myCodeBehind" Language="C#" %>
<html>
<head><title>Presentation.aspx</title></head>
<body>

<form Runat="Server">

<asp:Button
Text="Click Here!"
OnClick="Button_Click"
Runat="Server" />

<p>

<asp:Label
ID="lblMessage"
Runat="Server" />

</form>

</body>
</html>

There is a parser error - cannot find myCodeBehind. So the first line of the aspx file is at fault - but what is wrong?

Any ideas?

DJ