GridView 分页有关问题

GridView 分页问题
我是将GridView帮定到自定义实体集合.代码如下:
using   System;
using   System.Data;
using   System.Configuration;
using   System.Collections;
using   System.Collections.Generic;
using   System.Web;
using   System.Web.Security;
using   System.Web.UI;
using   System.Web.UI.WebControls;
using   System.Web.UI.WebControls.WebParts;
using   System.Web.UI.HtmlControls;

using   ISCAP.PrintReport.ReportModel;

public   partial   class   _Default   :   System.Web.UI.Page
{
        private   List <Customer>   customers;
        protected   void   Page_Load(object   sender,   EventArgs   e)
        {
                if   (!Page.IsPostBack)
                {
                        customers   =   Customer.GetAllCustomers();

                        gridViewCustomers.DataSource   =   Customer.GetAllCustomers();
                        gridViewCustomers.DataBind();
                }
        }
        protected   void   gridViewCustomers_SelectedIndexChanging(object   sender,   GridViewSelectEventArgs   e)
        {
                gridViewCustomers.PageIndex   =   e.NewSelectedIndex;
                gridViewCustomers.DataBind();
        }
}

运行时点击GridView页数,出现以下错误:
The   GridView   'gridViewCustomers '   fired   event   PageIndexChanging   which   wasn 't   handled.

请问这个问题可能出现的原因是什么?


[解决办法]
要用下面的这个事件
PageIndexChanging
中的e.NewPageIndex