'HttpContext' does not exist in the class or...

This is the error message I am getting:

"The type or namespace name 'HttpContext' does not exist in the class or namespace 'System.Web' (are you missing an assembly reference?)"

And this is the code:
--------------------------------
using System;
using System.Web;

namespace RecipeBox
{
//Business logic for User
public class bUser :Business
{
protected HttpContext oCurrentContext;

public bUser()
{
oCurrentContext= HttpContext.Current;
}
----------------------------

When I start typing in System.Web. VS only gives me 3 suggestions (AspNetHostingPermissions), whereas in another project, which as far as I can see is completely the same, I am given all the System.Web functions, not just the ones in System(Web).

Is there anybody out there that can tell me what I am doing wrong? Please :) Any help would be greatly appreciated.