Deserialisation Issues

using System;
using Newtonsoft.Json;
using System.Runtime.Serialization;

using System.Collections.Generic;

namespace DeserialisationTest
{
    [DataContract]
    class RootType
    {
        [DataMember(IsRequired = true)]
        public Dictionary<string, FooType> things { get; set; }
    }

    [DataContract]
    class FooType
    {
        [DataMember(IsRequired = true)]
        public double x { get; set; }

        [DataMember(IsRequired = true)]
        public double y { get; set; }

        [DataMember(IsRequired = true)]
        public List<int> a { get; set; }

        //[DataMember(Name = "z")]
        //public List<bool> zList { get; set; }

        [DataMember(Name = "z")]
        public Dictionary<string, bool> zDict { get; set; }
}

    class MainClass
    {
        public static void Main (string[] args)
        {

            string jsonString = "{\"things\":{\"1\":{\"x\":123.45,\"y\":678.9,\"z\":{\"2\":true},\"a\":[1,2]},\"2\":{\"x\":1414.23,\"y\":5656.78,\"z\":[true],\"a\":[3]}}}";
            string jsonStringD = "{\"things\":{\"1\":{\"x\":123.45,\"y\":678.9,\"z\":{\"2\":true},\"a\":[1,2]}}}";
            string jsonStringL = "{\"things\":{\"2\":{\"x\":1414.23,\"y\":5656.78,\"z\":[true],\"a\":[3]}}}";

            RootType rt = JsonConvert.DeserializeObject<RootType>(jsonStringD);
            Console.WriteLine (rt.things["1"].zDict["2"]);
            //Console.WriteLine (rt.things["2"].zList[0]);
        }
    }
}