I keep getting this error: "The type or namespace name 'SaveFileProvider' could not be found (are you missing a using directive or an assembly reference?) "

I know that I'm missing reference, but I'm referencing everything I can think of to reference, but it's still not picking it up.
Please see below all that I'm using: 

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Threading;
using Infragistics.Controls.Grids;
using Infragistics.Documents.Excel;
using Infragistics.Olap;
using Infragistics.Olap.Data;
using Infragistics.Olap.FlatData;

Here is the problem bit of code in which the only error I am getting is the fact that SaveFileProvider can't be found
 

private void SaveExport(Workbook dataWorkbook)
{

SaveFileProvider saveProvider = new SaveFileProvider();
saveProvider.Dialog.DefaultExt = "xls";

bool? showDialog = saveProvider.Dialog.ShowDialog();

if (showDialog == true)
{

using (Stream exportStream = saveProvider.Dialog.OpenFile())

{

dataWorkbook.Save(exportStream);
exportStream.Close();

}

}

What exactly am I doing wrong here?