(调查问卷)被选则的项与提交数据库的不一样??

数据库中的表:
index int ,name nchar(10),count int.
C#程序如下:
using System;
using System.Data;
using System.Configuration;
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 System.Data.SqlClient;
using System.Drawing.Imaging;

public partial class _Default : System.Web.UI.Page
{
    private SqlConnection conn;
    private DataSet ds = new DataSet();
    private string conString= ConfigurationSettings.AppSettings["conString"];
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack )
        {
            BindData();


        }


    }
    private void BindData()
    {
         conn =new  SqlConnection(conString );
        //创建sql语句
        string sql = "select *from city";
        //创建datadpater
        SqlDataAdapter da = new SqlDataAdapter(sql,conn );
        //填充dataset
        da.Fill(ds  ,"Data");
        //给RadioButtonList赋数据
        InitRadioButtonList();
        DataResult();


    }
    int  cityCount=0;
    private void DataResult()
    {
        foreach (DataRow aRow in ds.Tables["Data"].Rows)
        {
            cityCount += int.Parse(aRow["count"].ToString());

        }
        this.Label3.Text = "一个有" + cityCount + "人参加调查";

    }
    private void InitRadioButtonList()
    {
       this .RadioButtonList1 .DataSource =ds.Tables ["Data"];
       this.RadioButtonList1.DataTextField = ds.Tables["Data"].Columns["name"].ToString();
       this.RadioButtonList1.DataValueField = ds.Tables["Data"].Columns["count"].ToString();
       this.RadioButtonList1.DataBind();
    }
    //投票
    protected void Button1_Click(object sender, EventArgs e)
    {
        if (this.RadioButtonList1.SelectedItem != null)
        {

            conn = new SqlConnection(conString );
            conn.Open();
            string sql = "update city set count=" +Convert .ToInt32 ( int.Parse(this.RadioButtonList1.SelectedValue) + 1) + " where name='" + this.RadioButtonList1.SelectedItem.Text +"'";
            SqlCommand cmd = new SqlCommand(sql ,conn );
            this.Label2.Text = "你选择了" + this.RadioButtonList1.SelectedItem.Text;
            cmd.ExecuteNonQuery();
            conn.Close();
            this.Label2.Visible = true;
            this.Label3.Visible = false;
            BindData();
        }

    }
    //查看结果
    protected void Button2_Click(object sender, EventArgs e)
    {

        this.Label3.Visible = true;


    }

}
问题:有时我选择第二项时,它提交的是第一项的答案.还有调查的结果用百分比显示,怎么实现. --------------------编程问答-------------------- 一个劲顶接分

补充：.NET技术 ,  C#