AutoComplete from database

I m having problem when implementing autocompleteextender in visual studio 2008, where when i enter my any text in my textbox,it will automaticly capture the keywords and suggest words from database..no errors found,but it didnt works when i enter any keyword inside the textbox..
This is my aspx file :
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>



   


   

       
       
       
       
       
       

           
                            runat="server"
                ID="autoComplete1"
                TargetControlID="myTextBox"
                ServicePath="AutoComplete.asmx"
                ServiceMethod="GetCompletionList"
                MinimumPrefixLength="2"
                CompletionInterval="1000"
                EnableCaching="true"
                CompletionSetCount="12" />
   

   

This is my asmx.cs file:
using System;
using System.Web;
using System.Collections;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

///

/// Summary description for AutoComplete
///

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService]

public class AutoComplete : System.Web.Services.WebService
{
    [WebMethod]
    public string[] GetCompletionList(string prefixText)
    {
        DataSet dtst = new DataSet();
        SqlConnection sqlCon = new SqlConnection(ConfigurationManager.AppSettings["%$ ConnectionStrings:C:\PROGRAM FILES\MICROSOFT SQL SERVER\MSSQL.1\MSSQL\DATA\DATABASE1.MDFConnectionString %"]);
        string strSql = "SELECT Company_Name FROM Table1 WHERE CompanyName LIKE '" + prefixText + "%' ";
        SqlCommand sqlComd = new SqlCommand(strSql, sqlCon);
        sqlCon.Open();
        SqlDataAdapter sqlAdpt = new SqlDataAdapter();
        sqlAdpt.SelectCommand = sqlComd;
        sqlAdpt.Fill(dtst);
        string[] cntName = new string[dtst.Tables[0].Rows.Count];
        int i = 0;
        try
        {
            foreach (DataRow rdr in dtst.Tables[0].Rows)
            {
                cntName.SetValue(rdr["CompanyName"].ToString(), i);
                i++;
            }
        }
        catch { }
        finally
        {
            sqlCon.Close();
        }
        return cntName;
    }
}

Should i modify any code part?
Can i use the autocompleteextender using sqldatasource to call database?
Any ideas will be much appreciated.

Reference:http://www.c-sharpcorner.com/UploadFile/munnamax/AutocompleteExtender08062007113854AM/AutocompleteExtender.aspx