VS2005中对Session的使用问题

namespace Employee_Directory
{
    using System;
    using System.Collections;
    using System.ComponentModel;
    using System.Data;
    using System.Data.OleDb;
    using System.Drawing;
    using System.Web;
    using System.Web.SessionState;
    using System.Web.UI;
    using System.Web.UI.WebControls;
    using System.Web.UI.HtmlControls;
    //下面定义的PositionData类用于设置和获取当前页面信息。
    public class PositionData
    {
        private string name;
        private string CatID;
        //构造函数
        public PositionData(string Name, string CategoryID)
        {
            this.name = Name;
            this.CatID = CategoryID;
        }
        public string Name
        {
            get
            {
                return name;
            }
        }
        public string CategoryID
        {
            get
            {
                return CatID;
            }
        }
    }
    //定义CCutility类，定义全局变量
    public class CCUtility
    {
        public const int FIELD_TYPE_Text = 0;
        public const int FIELD_TYPE_Number = 1;
        public const int FIELD_TYPE_Date = 2;
        public const int FIELD_TYPE_Memo = 3;
        protected HttpSessionState Sesstion;
        protected HttpServerUtility Server;
        protected HttpRequest Request;
        protected HttpResponse Response;
        //CCUtility类构造函数
        public CCUtility(object parent)
        {
            DBOpen();
            try
            {
                Session = ((System.Web.UI.Page)parent).Session;
                Server = ((System.Web.UI.Page)parent).Server;
                Request = ((System.Web.UI.Page)parent).Request;
                Response = ((System.Web.UI.Page)parent).Response;
            }
            catch
            {
                Session = ((System.Web.UI.UserControl)parent).Session;
                Server = ((System.Web.UI.UserControl)parent).Server;
                Request = ((System.Web.UI.UserControl)parent).Request;
                Response = ((System.Web.UI.UserControl)parent).Response;
            }        }在调试时 出现错误D:\My Documents\Visual Studio 2005\WebSites\SIMS\App_Code\CCUtility.cs(59,17): 错误 CS0103: 当前上下文中不存在名称“Session”
D:\My Documents\Visual Studio 2005\WebSites\SIMS\App_Code\CCUtility.cs(66,17): 错误 CS0103: 当前上下文中不存在名称“Session”找了很久,一直找不到问题出在哪里.用的VS2005.