[jQuery] JSON with .Net

[JQueryProgrammer]

I am trying to use JSON with jquery and .Net. I am using json2.js for
JavaScript and Newtonsoft.JSON for .Net serialization. Here goes my
code:

JavaScript
-------------------------------------------------------------------
$.ajax({
        url: "http://localhost/JSONSample/default.aspx";,
        method: "GET",
        datatype: "json",
        contentType: "application/json; charset=utf-8",
        data: {name: 'User'},
        success: function(result) {
                var oResult = JSON.parse(result);
                alert(oResult.Guid);
        },
        error: function() {
                alert("Some error occured");
        }
});

Server side code
--------------------------------------------------------------------
protected void Page_Load(object sender, EventArgs e)
{
        if(Request.Params["name"] != null && Request.Params["name"].ToString
() != "")
        {
                GetName();
        }
}

public void GetName()
{
        System.Web.Script.Serialization ser = new
System.Web.Script.Serialization();
        System.Text.StringBuilder oBuilder = new System.Text.StringBuilder();

        oBuilder.Append("{");
        oBuilder.AppendFormat("'{0}' : '{1}'", "Guid", Guid.NewGuid());
        oBuilder.Append("}");

        string json = ser.Serialize(oBuilder.ToString());
        Response.Write(json);
        Response.Flush();
        Response.Close();
}

I am able to get the result in success function. But the oResult.Guid
is undefined. When I am trying to alert oResult, it gives me:

{ 'Guid' : '16ba666a-cd2a-41b6-b0b1-5f072d44d488' }

Can anyone help me why is the oResult.Guid undefined..?