Returning JSON in a asp.net (vb) web service

I've tried to return a JSON string from my asp.net (vb) webservice using something like this:

<WebMethod()> _
<ScriptMethod(ResponseFormat:=ResponseFormat.Json, UseHttpGet:=True)> _
Public Function Genex (ByVal id as String,ByVal type1 as Integer,ByVal xtext As string) As String

but I receive this error: "ScriptMethod is not defined".

If I include "Imports System.Runtime.Serialization" there is no JSON method or class.
How do I include it?

if I declare my WebMethod as:
<WebMethod()> _
Public Function Genex (ByVal id as String,ByVal type1 as Integer,ByVal xtext As string) As String

my webservice works fine but it responds with an XML string, I need that it responds with a JSON string
BemboXAsked:
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Kiran SonawaneProject LeadCommented:
You need to add reference of System.Web.Extensions assembly in order ScriptMethod brings in a scrope
http://www.codeproject.com/Articles/45275/Create-a-JSON-WebService-in-ASP-NET-2-0-with-a-jQu
BemboXAuthor Commented:
Do I need to install a library like json.net from json.codeplex.com or it is already included in the framework?
BuggyCoderCommented:
when you specify your response format, it automatically serializes your response using Json Serializer, you can read more about it here:-

http://msdn.microsoft.com/en-us/library/system.web.script.serialization.javascriptserializer.aspx

so there is no need to install anything on service side.

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BemboXAuthor Commented:
Thanks.
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