My graph doesnt appear on my form...

Question

Hi!

I cannot see appearing my graph on my form.
The first error message I receive is:

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

The segond is: 

The name 'SeriesChartType' does not exist in the current context

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Data.SqlClient;

using System.Web.UI.DataVisualization.Charting;//The first Error message it's here

namespace WindowsFormsApplication1

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            SqlConnection conn = new SqlConnection("Data Source=localhost\\sqlexpress;Initial Catalog=master;Integrated Security=True");

            string qry = "select Name, salary from salary from employee";

            SqlDataAdapter da = new SqlDataAdapter(qry, conn);

            DataSet ds = new DataSet();

            da.Fill(ds,"salary");

            chart1.Series["Series1"].XValueMember="name";

            chart1.Series["Series2"].YValueMembers="salary";

            this.chart1.Titles.Add("employee salary");

            chart1.Series["series1"].ChartType = SeriesChartType.Pie;// the Segond error message it's here

            chart1.Series["series1"].IsValueShownAsLabel = true;

        }

    }

}