method error 500 in my ajax cascading dropdown list

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">


            <asp:DropDownList id="dropcity" runat="server"  AutoPostBack="true" class="ddl" style="width:210px; height:30px; background-color:#40E0D0"></asp:DropDownList>

              <cc1:CascadingDropDown ID="dropcitycc" TargetControlID="dropcity" PromptText="Select City"
                PromptValue=""  runat="server"
                Category="dropcity" ServicePath="~/DropDownCasCad.asmx" ServiceMethod="GetData"  LoadingText="Loading..." />

          <asp:DropDownList id="dropmovie" runat="server" class="ddl" style="width:210px; height:30px; background-color:#40E0D0"></asp:DropDownList>
           <cc1:CascadingDropDown ID="dropmoviecc" TargetControlID="dropmovie" PromptText="Select Movie"
                PromptValue=""  runat="server"
                Category="dropmovie" LoadingText="Loading..." ServicePath="~/DropDownCasCad.asmx" ServiceMethod="GetData"  ParentControlID="dropcity"/>

          <asp:DropDownList id="dropdate" runat="server" class="ddl" style="width:210px; height:30px; background-color:#40E0D0"></asp:DropDownList>
          <cc1:CascadingDropDown ID="dropdatecc" TargetControlID="dropdate" PromptText="Select date"
                PromptValue=""  runat="server"
                Category="dropdate" LoadingText="Loading..."  ServicePath="~/DropDownCasCad.asmx" ServiceMethod="GetData"  ParentControlID="dropmovie"/>

</asp:Content>

<%@ WebService Language="C#" CodeBehind="DropDownCasCad.asmx.cs" Class="easymoviesindia.DropDownCasCad" %>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Collections.Specialized;
using System.Web.Services;
using AjaxControlToolkit;

namespace easymoviesindia
{
    /// <summary>
    /// Summary description for DropDownCasCad
    /// </summary>

[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
 
    // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
     //[System.Web.Script.Services.ScriptService]
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.Web.Script.Services.ScriptService()]
   //  [System.Web.Script.Services.ScriptService()]
    public class DropDownCasCad : System.Web.Services.WebService
    {
         public DropDownCasCad(){
         }

        public List<cascadingdropdownnamevalue> bind(string[] total_moviedetails) //--------------------------------------bind method begin
        {
            List<cascadingdropdownnamevalue> list = new List<cascadingdropdownnamevalue>();

            string[] singlemoviedetails = null;

            list.Add(new CascadingDropDownNameValue("TELUGU", "TELUGU"));


            foreach (string single_moviedetails in total_moviedetails)
            {
                singlemoviedetails = single_moviedetails.Split('~');


                if ("TELUGU".Equals(singlemoviedetails[2].ToString()))
                {
                    list.Add(new CascadingDropDownNameValue(singlemoviedetails[1].ToString(), singlemoviedetails[0].ToString()));
                }//if
            }

            bool isHindi = true;
            foreach (string single_moviedetails in total_moviedetails)
            {

                singlemoviedetails = single_moviedetails.Split('~');

                if ("HINDI".Equals(singlemoviedetails[2].ToString()))
                {
                    if (isHindi)
                    {
                        list.Add(new CascadingDropDownNameValue("HINDI", "HINDI"));
                        isHindi = false;
                    }
                    list.Add(new CascadingDropDownNameValue(singlemoviedetails[1].ToString(), singlemoviedetails[0].ToString()));

                }

            }

            bool isEnglish = true;
            foreach (string single_moviedetails in total_moviedetails)
            {

                singlemoviedetails = single_moviedetails.Split('~');

                if ("ENGLISH".Equals(singlemoviedetails[2].ToString()))
                {
                    if (isEnglish)
                    {
                        list.Add(new CascadingDropDownNameValue("ENGLISH", "ENGLISH"));
                        isEnglish = false;

                    }

                    list.Add(new CascadingDropDownNameValue(singlemoviedetails[1].ToString(), singlemoviedetails[0].ToString()));
                }

            }

            return list;
        }

        protected List<cascadingdropdownnamevalue> datesprocess(string dateDirPath, string knownvalue)
        {

            DataBindToDateProcess dates = new DataBindToDateProcess();
            List<cascadingdropdownnamevalue> list = new List<cascadingdropdownnamevalue>();

            ArrayList dateslist = dates.BindProcess(dateDirPath, knownvalue);

            foreach (string date in dateslist)
            {
                DateTime d = new DateTime(Convert.ToInt32(date.Substring(0, 4).Trim()), Convert.ToInt32(date.Substring(4, 2).Trim()), Convert.ToInt32(date.Substring(date.Length - 2).Trim()));
                list.Add(new CascadingDropDownNameValue(d.ToString("ddd MMM dd yyyy"), date));
            }
            return list;
        }

        [System.Web.Services.WebMethod]
        
       // [System.Web.Script.Services.ScriptMethod]
        public static AjaxControlToolkit.CascadingDropDownNameValue[] GetData(string knownCategoryValues, string category)
        {
            //string dateDirPath = "D:\\easy100services\\cities\\" + dropcity.SelectedValue + "\\movieticketing";
            string dateDirPath = "D:\\easy100services\\cities\\";

            string cityurl = "http://xxx.xxx/xyz/site/abc.asp?citycode=";
            DataBindToMovieProcess movies = new DataBindToMovieProcess();
            DataBindToDateProcess dates = new DataBindToDateProcess();
            DropDownCasCad t = new DropDownCasCad();
            List<cascadingdropdownnamevalue> vls;

            // Get a dictionary of known category/value pairs  
            StringDictionary known = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
            AjaxControlToolkit.CascadingDropDownNameValue[] values = null;
            switch (category)
            {
                case "dropcity":
                    values = new AjaxControlToolkit.CascadingDropDownNameValue[] {  
                    new AjaxControlToolkit.CascadingDropDownNameValue("Hyderabad", "1"),  
                    new AjaxControlToolkit.CascadingDropDownNameValue("Warangal", "20"),  
                    new AjaxControlToolkit.CascadingDropDownNameValue("kakinada", "9"),  
                };
                    break;
                case "dropmovie":
                    switch (known["dropcity"])
                    {
                        case "1":
                            cityurl = cityurl + known["dropcity"];
                            dateDirPath = dateDirPath + known["dropcity"];
                            vls = t.bind(movies.BindProcess(cityurl));
                            values = vls.ToArray<cascadingdropdownnamevalue>();
                            break;

                        case "20":
                            cityurl = cityurl + known["dropcity"];
                            dateDirPath = dateDirPath + known["dropcity"];
                            vls = t.bind(movies.BindProcess(cityurl));
                            values = vls.ToArray<cascadingdropdownnamevalue>();
                            break;

                        case "9":
                            cityurl = cityurl + known["dropcity"];
                            dateDirPath = dateDirPath + known["dropcity"];
                            vls = t.bind(movies.BindProcess(cityurl));
                            values = vls.ToArray<cascadingdropdownnamevalue>();
                            break;

                        default:
                            break;
                    }
                    break;
                case "dropdate":
                    dateDirPath = dateDirPath + known["dropcity"] + "\\movieticketing";
                    values = t.datesprocess(dateDirPath, known["dropmovie"]).ToArray<cascadingdropdownnamevalue>();

                    break;
            }
            return values;
        }


    }
}