' "Chatengine" does not exist in yhe current context' someone help me to solve this

hi i'm new to asp.net. now i'm trying to develope a project something related to mailfetcher. in a global asax page i got some error.  some one plz help me to solve this yaar...!

Global.asax.cs


using System;
using System.Threading ;
using System.Collections;
using System.ComponentModel;
using System.Web;
using System.Web.SessionState;

namespace ASPNETChat
{
/// <summary>
/// Summary description for Global.
/// </summary>
public class Global : System.Web.HttpApplication
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;

public Global()
{
InitializeComponent();
}
Timer ChatRoomsCleanerTimer=new System.Threading.Timer(new TimerCallback(ChatEngine.CleanChatRooms),null,3600000,3600000);
protected void Application_Start(Object sender, EventArgs e)
{

}

protected void Session_Start(Object sender, EventArgs e)
{

}

protected void Application_BeginRequest(Object sender, EventArgs e)
{

}

protected void Application_EndRequest(Object sender, EventArgs e)
{

}

protected void Application_AuthenticateRequest(Object sender, EventArgs e)
{

}

protected void Application_Error(Object sender, EventArgs e)
{

}

protected void Session_End(Object sender, EventArgs e)
{

}

protected void Application_End(Object sender, EventArgs e)
{

}

#region Web Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.components = new System.ComponentModel.Container();
}
#endregion
}
}


i got this type of error: " The name 'ChatEngine' does not exist in the current context."