Im getting error on visual studio 2010: The type or namespace name 'HttpUtility' does not exist

How can i solve it ? If im doing in my code: using System.Web; it dosent help I tried ot add reference of System.Web.ApplicationServices didnt help also tried to reference: System.WebServices Didnt help either. This is the only two references that are using Web i have in the visual studio 2010 .net references list.

The line is:

var queryString = System.Web.HttpUtility.ParseQueryString(url);

The error is on the: HttpUtility

Error 1 The type or namespace name 'HttpUtility' does not exist in the namespace 'System.Web' (are you missing an assembly reference?)

The project is set on Target Framework to: .net 4 client profile. I have windows 8 64bit.