gridview分页时的问题

代码运行提示未将对像引用设置到对像实例，请高手帮忙看看。错误处已标明    
        string sql1 = "";         int rowCount = 0;        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {                this.xianshi();            }
        }
  
        public SqlConnection GetConnection()
        {
            string myStr = ConfigurationManager.AppSettings["conn"].ToString();
            SqlConnection myConn = new SqlConnection(myStr);
            return myConn;
        }        private void xianshi()
        {            
            SqlConnection myConn = GetConnection();
            myConn.Open();
            sql1 = this.fkcx_jj.Text;
            string sqlStr = "select * from gg_gg,gg_zt where gg_gg.gg_fkzt=gg_zt.ggzt_id  order by gg_zt.ggzt_mc";
            DataSet ds = new DataSet();
            SqlDataAdapter da = new SqlDataAdapter(sqlStr, myConn);
           
            da.Fill(ds,"gg_gg");
            rowCount = ds.Tables["gg_gg"].Rows.Count;
            fkcx_gv.DataSource=ds.Tables["gg_gg"];
            fkcx_gv.DataBind();        }
   
        protected void NavigateToPage(object sender, CommandEventArgs e)
        {
            switch (e.CommandArgument.ToString())//控制转页
            {
                case "First"://首页
                    this.fkcx_gv.PageIndex = 0;
                    break;
                case "Prev"://上一页
                    if (this.fkcx_gv.PageIndex > 0)
                        this.fkcx_gv.PageIndex -= 1;
                    break;
                case "Next"://下一页
                    if (this.fkcx_gv.PageIndex < (this.fkcx_gv.PageCount - 1))
                        this.fkcx_gv.PageIndex += 1;
                    break;
                case "Last"://尾页
                    this.fkcx_gv.PageIndex = this.fkcx_gv.PageCount - 1;
                    break;
            }
            xianshi();
        }
  
        protected void fkcx_gv_DataBound(object sender, EventArgs e)
        {
            GridViewRow pagerRow = fkcx_gv.BottomPagerRow;
 
            Label lblCurrent = (Label)pagerRow.Cells[0].FindControl("lblPageCurrent");//发生错误的地方
            Label lblCount = (Label)pagerRow.Cells[0].FindControl("lblPageCount");
            Label lblRow = (Label)pagerRow.Cells[0].FindControl("lblPageRow");
            // 获取按钮实例，为了控制其是否可用
            LinkButton btnFirstTem = (LinkButton)pagerRow.Cells[0].FindControl("btnFirst");
            LinkButton btnPrevTem = (LinkButton)pagerRow.Cells[0].FindControl("btnPrev");
            LinkButton btnNextTem = (LinkButton)pagerRow.Cells[0].FindControl("btnNext");
            LinkButton btnLastTem = (LinkButton)pagerRow.Cells[0].FindControl("btnLast");            if (lblCurrent.Text != null)
                lblCurrent.Text = (this.fkcx_gv.PageIndex + 1).ToString();
            if (lblCount != null)
                lblCount.Text = this.fkcx_gv.PageCount.ToString();
            if (lblRow != null)
                lblRow.Text = rowCount.ToString();
            if (this.fkcx_gv.PageIndex == 0)
            {
                btnFirstTem.Enabled = false;
                btnPrevTem.Enabled = false;
                
                if (this.fkcx_gv.PageCount == 1)
                {
                    btnNextTem.Enabled = false;
                    btnLastTem.Enabled = false;
                }
            }
            else if (this.fkcx_gv.PageIndex == (this.fkcx_gv.PageCount - 1))
            {
                btnNextTem.Enabled = false;
                btnLastTem.Enabled = false;
            }
        }
    }
}