I'm having js function which calls mvc controller action method which return list of data as json.

function FillCountryCities(countryId) {
                $.ajax({
                    type: 'GET',
                    url: '/User/FillCityCombo',
                    data: { countryId: countryId },
                    contentType: 'application/json',
                    success: function (data) {
                        alert(data[0].Name);
                    }
                    error: function () { alert('something bad happened'); }
....

format of data which sent back from controller is Name (string) and Id (Guid)

Now I just want to alert Name on success first item from collection. Double checked controller sends 20 records, so it should alert first from collection but I'm getting error something bad happened

update:

public JsonResult FillCityCombo(Guid countryId) {
var cities = repository.GetData() .Where(x => x.Country.Id == countryId).ToList();

        if (Request.IsAjaxRequest())
        {
            return new JsonResult
            {
                Data = cities,
                JsonRequestBehavior = JsonRequestBehavior.AllowGet
            };
        }
        else
        {
            return new JsonResult
            {
                Data = "Not Valid Request",
                JsonRequestBehavior = JsonRequestBehavior.AllowGet
            };
        }            
    }