hi ... iam getting error in default.aspx page

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Text;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
 
public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Raj.changerate rs = new Raj.changerate();
        DataSet ds = rs.getrates();
        GridView1.DataSource = ds.Tables[0];
        GridView1.DataBind();
    }
 
}

Error   1   Reference.svcmap: Could not load file or assembly 'itextsharp, Version=5.5.0.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' or one of its dependencies. The system cannot find the file specified.    App_WebReferences/ServiceReference1/
Error   2   The type or namespace name 'changerate' does not exist in the namespace 'Raj' (are you missing an assembly reference?)  E:\mine\WebSiteD\Default.aspx.cs    16  13  WebSiteD
Error   3   The type or namespace name 'changerate' does not exist in the namespace 'Raj' (are you missing an assembly reference?)  E:\mine\WebSiteD\Default.aspx.cs    16  37  WebSiteD