.NET 4.x Как исправить ошибку в коде RSS-парсера - C#

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;
 
namespace rssPars
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        String[,] rssData = null;
 
        private String[,] getRssData(String channel)
        {
            System.Net.WebRequest myRequest = System.Net.WebRequest.Create(channel);
            System.Net.WebResponse myResponse = myRequest.GetResponse();
 
            System.IO.Stream rssStream = MyResponse.GetResponseStream();
            System.Xml.XmlDocument rssDoc = new System.Xml.XmlDocument();
 
            rssDoc.Load(rssStream);
 
            System.Xml.XmlNodeList rssItems = rssDoc.SelectNodes("rss/channel/item");
 
            String[,] tempRssData = new String[100, 3];
 
            for (int i = 0; i < rssItems.Count; i++)
            {
                System.Xml.XmlNode rssNode;
 
                rssNode = rssItems.Item(i).SelectSingleNode("title");
                if (rssNode != null)
                {
                    tempRssData[i,0] = rssNode.InnerText;
                }
                else
                {
                    tempRssData[i,0] = "";
 
                }
                rssNode = rssItems.Item(i).SelectSingleNode("discription");
                if (rssNode != null)
                {
                    tempRssData[i, 1] = rssNode.InnerText;
                }
                else
                {
                    tempRssData[i, 1] = "";
                }
                rssNode = rssItems.Item(i).SelectSingleNode("link");
                if (rssNode != null)
                {
                    tempRssData[i,2] = rssNode.InnerText;
                }
                  else
                {
                    tempRssData[i,2] = "";
 
                }
           }
 
           return tempRssData;

       }

        private void refreshButton_Click(object sender, EventArgs e)
        {
            titlesComboBox.Items.Clear();
            rssData = getRssData(ChannelTextBox.Text);
            for (int i = 0; i < rssData.GetLength(0); i++)
            {
                if (rssData[i, 0] != null)
                {
                    titlesComboBox.Items.Add(rssData[i, 0]);
                }
                titlesComboBox.SelectedIndex = 0;
            }
 
        }
 
        private void titlesComboBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (rssData[titlesComboBox.SelectedIndex, 1] != null)
                decriptionTextBox.Text = rssData[titlesComboBox.SelectedIndex, 1];
            if (rssData[titlesComboBox.SelectedIndex, 2] != null)
                linkLabel1.Text = "GoTo: " + rssData[titlesComboBox.SelectedIndex, 0];
        }
 
        private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
             if (rssData[titlesComboBox.SelectedIndex, 2] != null)
                 System.Diagnostics.Process.Start(rssData[titlesComboBox.SelectedIndex, 2]);
        }
    }
}