子类的Page_Load没有被触发,该如何解决

public partial class BasePage : Page
    {
        protected override void OnLoad(EventArgs e)
        {

            // 业务逻辑

            base.OnLoad(e);
        }

        public string BaseUrl { get; set; }
    }

public partial class Login : BasePage
    {
        protected override void Page_Load(object sender, EventArgs e)
        {
            -- 此处程序都没有执行到
            if (!IsPostBack) -- 断点在这里
            {
                string strUserID = string.Empty;
                if (Request.Params["userid"] != null)
                {
                    strUserID = Request.Params["userid"].ToString();
                }
            }
        }
    }

public class BasePage:Page
    {
        public BasePage() 
        {
            this.Load += new EventHandler(CheckSession_Load);
            //PublicMethods.ReturnClientPosition(this);
        }
        //protected override void OnInit(EventArgs e)
        //{
        //    this.Load += new EventHandler(CheckSession_Load);
        //    base.OnInit(e);

        //}
        //protected override void OnLoad(EventArgs e)
        //{

        //    //一些要在Page_Load的时候执行的代码
        //    base.OnLoad(e);

        //}

        /// <summary>
        /// 用来判断session是否还保持
        /// </summary>
        protected void CheckSession_Load(object sender, EventArgs e) 
        {
            PublicMethods.IsSessionActive(this);
        }
       

    }