Cannot Resolve: "The name 'Directory' does not exist in the current context"

I am trying to run this code sample located at GHI Electronics – Where Hardware Meets Software

However I have been unsuccessful trying to resolve this compile error “The name ‘Directory’ does not exist in the current context”

I have the following using statements and all the dll references are from the 4.1 SDK library.

using System;
using System.IO;
using System.Threading;

using Microsoft.SPOT;
using Microsoft.SPOT.IO;

using GHIElectronics.NETMF.IO;
using Microsoft.SPOT.Hardware;
using GHIElectronics.NETMF.USBClient;
using GHIElectronics.NETMF.USBHost;
using GHIElectronics.NETMF.Hardware;

As Rajesh said in the other post, Directory is in System.IO. Have you included it as one of your References? Remember, USING is just a name shortcut to something Visual Studio can see the code for; without adding the Reference the USING has no value. (I have just tested this on an existing 4.1 project myself, deleting the reference to bought up that error)

indeed. yes thanks