How to enable dropdownlist using jquery

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C#

jQuery

webservice

I have 2 dropdownlist and 1 textbox i m filling dropdown using webservice..
District DistrictCode
bangalore 1
chennai 2
mumbai 3
Two dropdownlist names are ddldistrict,ddltaluk( here ddldistrict is parent, ddltaluk is child)
textbox name is txtdistrictcode
if i selected ddldistrict like bangalore,chennai,mumbai that concerned districtid will bind in the txtdistrictcode textbox and concerned taluk will fill in the ddltaluk Let's say if i selected bangalore in ddldistrict for that bangalore id is 1 so 1 ll bind in the districtid textbox that is working fine.Now the problem is if i type 1 in ddldistrictid the concerned bangalore should bind in the ddldistrict that also working fine but the child textbox(ddltaluk) is not filling and it is disabled. But if i selected ddldistrict bangalore the districtid is binding and taluk is also filling.

I used jquery for bidirection binding( ddldistrict to txtdistrictid and txtdistrictid to ddldistrict)

$("#ContentPlaceHolder1_ddlDistrict").live("change", function () {
            var selectedText = $("#ContentPlaceHolder1_ddlDistrict option:selected").val();
            if (selectedText != "") {
                $('#ContentPlaceHolder1_txtDistrict_Code_I').val(selectedText);
            }
            else if (selectedText == "") {
                $('.ajax__validatorcallout_popup_table_row').hide();
                $('#ContentPlaceHolder1_ddlDistrict').focus();
                $('#ContentPlaceHolder1_txtDistrict_Code_I').val('');
            }
            else {
                $('#ContentPlaceHolder1_txtDistrict_Code_I').val('');
                $('#ContentPlaceHolder1_ddlDistrict').val('');
                alert('There is no Code for Selected District');
                $('#ContentPlaceHolder1_ddlDistrict').focus();
            }
        });

        $("#ContentPlaceHolder1_txtDistrict_Code_I").live("focusout", function () {
            var selectedText = $("#ContentPlaceHolder1_txtDistrict_Code_I").val();
            if (selectedText != "") {
                $('#ContentPlaceHolder1_ddlDistrict').val(selectedText);
                var selectedvalue = $("#ContentPlaceHolder1_ddlDistrict option:selected").val();
                if (selectedvalue == "") {
                    alert("Invalid District Code, Please Enter valid Code");
                    $("#ContentPlaceHolder1_txtDistrict_Code_I").val('');
                    $("#ContentPlaceHolder1_txtDistrict_Code_I").focus();
                }
            }
        });

For Filling Cascading dropdownlist i used webservices:
Parent Control

[WebMethod]
        public  Ajx[] get_Districts(string knownCategoryValues, string category)
        {
            DataTable dtMainModule = new DataTable();
            string StateID;

            StringDictionary MainModuleValues =  CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);

            StateID = "09";// MainModuleValues["StateID"];
            dtMainModule = odal.ReturnDt(@"select distinct fldDistrictCode,fldDistrictName from  bindDimpa.tblDistrict where fldStateID='" + StateID + "' order by fldDistrictName");
            List< Ajx> objMainModule = new List< Ajx>();

            foreach (DataRow dr in dtMainModule.Rows)
            {
                objMainModule.Add(new  Ajx(Convert.ToString(dr["fldDistrictName"]), Convert.ToString(dr["fldDistrictCode"])));
            }
            return objMainModule.ToArray();
        }
Child Control

[WebMethod]
        public CascadingDropDownNameValue[] getTaluks(string knownCategoryValues, string category)
        {
            
            DataTable dtMainModule = new DataTable();
            string fldDistrictID;

            StringDictionary MainModuleValues = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);

            fldDistrictID = MainModuleValues["DistrictID"];
            dtMainModule = odal.ReturnDt(@"select DISTINCT Dist_TehsilID,Tehsilaspercensus2001 from bindPS.tblVillage  where TehsilID is not null and DistrictID='" + fldDistrictID + "'");

            List<cascadingdropdownnamevalue> objMainModule = new List<cascadingdropdownnamevalue>();

            foreach (DataRow dr in dtMainModule.Rows)
            {
                objMainModule.Add(new CascadingDropDownNameValue(Convert.ToString(dr["Tehsilaspercensus2001"]), Convert.ToString(dr["Dist_TehsilID"])));
            }
            return objMainModule.ToArray();
        }</cascadingdropdownnamevalue></cascadingdropdownnamevalue>