Error in Updating service

[ERUM]

i have following code

using System.Data;
using System.Data.SqlClient;
using System;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Activation;
using System.Collections.Generic;
using System.Text;

namespace VotingPanel.Web
{
    [ServiceContract]  
    public interface Iservice1
    {
        [OperationContract]
        List<Vote> GetChartData();

        
    }
 [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
//    [ServiceContract]
    public class Service1 : Iservice1
    {

        
        SqlConnection Conn;
        SqlCommand Cmd;

        
        # region Iservice1 members
        [OperationContract]
        public List <Vote> GetChartData()

    {
       DataClasses1DataContext db = new DataClasses1DataContext();
       var query = from c in db.Votes select c;
       return query.Take(10).ToList();
        }
      # endregion
       
       
       [OperationContract]

        public void Insertdata(String vote, DateTime dt) 
        {
            Conn = new SqlConnection("Data Source=IRAM-PC;Initial Catalog=Voting;User Id=sa;Password=sa;Integrated Security=SSPI");
            Cmd = new SqlCommand();
            Conn.Open();
            Cmd.Connection = Conn;
            Cmd.CommandText = "insert into votes values  ('" + vote + "', '"+dt+"' )";

           
            int ins = Cmd.ExecuteNonQuery();
            //if (ins > 0) 
            //{ 
            //    Inserted = true; 
            //} 

            Conn.Close(); 
        }
        public void GetData()
        {
            bool Inserted = false;
            Conn = new SqlConnection("Data Source=IRAM-PC;Initial Catalog=Voting;User Id=sa;Password=sa;Integrated Security=SSPI");
            Cmd = new SqlCommand();
            Conn.Open();
            Cmd.Connection = Conn;
            Cmd.CommandText = "SELECT votingtext, COUNT(Votingtext) AS count FROM votes group by Votingtext";
           
           
            int ins = Cmd.ExecuteNonQuery();
            if (ins > 0)
            {
                Inserted = true;
            }

            Conn.Close();
            //return Inserted;
        } 

    
   

        // Add more operations here and mark them with [OperationContract]
        }
}

while updating service i m getting an error