Deserialize json array to list

I don't see a whole lot wrong with the code so I'm thinking your problem might be with the serialization itself. I have several websites written in PHP that I use JSON serialization and encrypted data to pull down orders that have come in through the sites instead of going to each database individually to process the orders. I accomplish this through Data Contracts in a C# app.
I've attached some snippets from a couple of my classes for example I hope they help answer your question.

First I set up a my data contract class

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

namespace WebOrders
{
    [DataContract]
    public class OrderItem
    {
        public OrderItem() { }

        [DataMember]
        public string orderID { get; set; }

        [DataMember]
        public string qty { get; set; }

        [DataMember]
        public string productID { get; set; }

        [DataMember]
        public string mfrPartNumber { get; set; }

        [DataMember]
        public string price { get; set; }
    }
}

Then I use a utility class that has a generic enumerator to handle all serialization and deserialization transactions...

public static IEnumerable<t> GetValues<t>()
{
    return Enum.GetValues(typeof(T)).Cast<t>();
}


public static string Serialize<t>(T obj)
{
    System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
    MemoryStream ms = new MemoryStream();
    serializer.WriteObject(ms, obj);
    string ret = Encoding.Default.GetString(ms.ToArray());
    ms.Dispose();
    return ret;
}

public static T Deserialize<t>(string json)
{
    T obj = Activator.CreateInstance<t>();
    MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json));
    System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
    obj = (T)serializer.ReadObject(ms);
    ms.Close();
    ms.Dispose();
    return obj;
}

Usage is as follows:

OrderItem orderitem = Deserialize<OrderItem>(o);

Hope you find this useful, I know I sure did...
-Smith