webservice call keeps returning json - web-services

Question

I'm just trying to test a very simple ajax call to a simple webservice. I'm using .net 4, iis 6. My webservice code looks like this...
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Web.Script.Services;
using System.Web.Script.Serialization;
namespace ABCNamespace {
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.ToolboxItem(false)]
[ScriptService]
public class MyService : System.Web.Services.WebService
{
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string HelloWorld()
{
return new JavaScriptSerializer().Serialize("Hello World");
}
}
}
My call looks like this
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "../../MyService.asmx/HelloWord",
data: "{}",
dataType: "json",
success: function () { alert('done'); },
error: function(XMLHttpRequest, textStatus, errorThrown) {
alert("Status: " + textStatus); alert("Error: " + errorThrown);
}
});
I'm keep getting 500 error and after taking a closer look, I'm getting a string back instead of json data. I think if correct this, it will fix my issue. However, I can't get it to return json data.
Here is a response check by invoking my webmethod
<?xml version="1.0" encoding="UTF-8"?>
<string xmlns="http://tempuri.org/"> "Hello World" </string>
Note: please ignore the fact that I'm using ../../ in my url instead of resolveURL. This is just for quick simple testing purposes. I also play around with the web.config handlers and no luck. Not sure what I miss...