Repeater分页出现:"输入字符串的格式不正确"

using System;
using System.Collections;
using
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
namespace _021Repeater
{
    /// <summary>
    /// WebForm1 的摘要说明。
    /// </summary>
    public class WebForm1 : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.Panel Panel1;
        protected System.Web.UI.WebControls.Label lable1;
        protected System.Web.UI.WebControls.Label lblCurPage;
        protected System.Web.UI.WebControls.Button btnPre;
        protected System.Web.UI.WebControls.Button btnNext;
        protected System.Web.UI.WebControls.Repeater Repeater2;

        private void Page_Load(object sender, System.EventArgs e)
        {
            
            // 在此处放置用户代码以初始化页面
            if(!Page.IsPostBack)
            {
                this.bindtoRepeater();
                this.lblCurPage.Text="1";
            }

        }
        private void bindtoRepeater()
    {    
            int curPage=Convert.ToInt16(this.lblCurPage.Text);//这里提示:"输入字符串的格式不正确"
        SqlConnection con=DB.createCon();
        con.Open();
        SqlDataAdapter sda=new SqlDataAdapter("select * from employees",con);
        DataSet ds=new DataSet();
        sda.Fill(ds,"emp");
        System.Web.UI.WebControls.PagedDataSource ps=new PagedDataSource();
        ps.DataSource=ds.Tables["emp"].DefaultView;
        ps.AllowPaging=true;
        ps.PageSize=3;
        ps.CurrentPageIndex=curPage-1;
        this.btnPre.Enabled=true;
            this.btnNext.Enabled=true;
            if(curPage==1)
            {
                this.btnPre.Enabled=false;
            }
            if(curPage==ps.PageCount)
            {
                this.btnNext.Enabled=false;
            }
        this.Repeater2.DataSource=ps;
        this.Repeater2.DataBind();
    }

        #region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {   
            this.btnPre.Click += new System.EventHandler(this.btnPre_Click);
            this.btnNext.Click += new System.EventHandler(this.btnNext_Click);
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion

        private void btnPre_Click(object sender, System.EventArgs e)
        {
            this.lblCurPage.Text=Convert.ToString(Convert.ToInt32(this.lblCurPage.Text)-1);
            this.bindtoRepeater();
        }

        private void btnNext_Click(object sender, System.EventArgs e)
        {
            this.lblCurPage.Text=Convert.ToString(Convert.ToInt32(this.lblCurPage.Text)+1);
            this.bindtoRepeater();
        }
    }
}