The type or namespace name 'Node' could not be found

[joyfreak]

here is a page to call a class in app_code folder\[code\]Line 11: protected void Page_Load(object sender, EventArgs e)Line 12: {Line 13: Node node = new Node();\[/code\]the error message is \[code\]The type or namespace name 'Node' could not be found\[/code\]the website is moved from a computer to this new server running 2008 server iis7.5, just installed asp.net framework 4.0. Any server setting will cause this error? The web app is working fine in old computer.thanks