HTML-Agility-Pack's DocumentNode.SelectNodes not able to find specific node
===

I am using HTML-Agility-Pack to scrape data about domains and IPs from the <a href="http://www.mcafee.com/us/mcafee-labs/threat-intelligence.aspx">Mcafee Threat Intelligence lab</a>, but no matter what XPATH I provide to DocumentNode.SelectNodes it cannot find the node I am looking for (the image for threat level). It can find other nodes and images, but not this specific one as far as I can tell.  The specific img has an id of "ctl00_mainContent_imgRisk" on this page: www.mcafee.com/threat-intelligence/domain/default.aspx?domain=facebook.com (facebook.com as an example). Here is the code I am using:

            string XPATH = "foo"
            string url = "http://www.mcafee.com/threat-intelligence/ip/default.aspx?";
            if (y == true)
                url = url + "ip=" + ipaddress;
            if (y == false)
                url = url + "domain=" + domainname;
            HttpWebRequest mcafeeReq = (HttpWebRequest)WebRequest.Create(url);
            mcafeeReq.UserAgent = @"Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5";
            HtmlDocument mcafeeWeb = new HtmlDocument();
            HttpWebResponse resp = (HttpWebResponse)mcafeeReq.GetResponse();
            var resultStream = resp.GetResponseStream();
            mcafeeWeb.Load(resultStream);
            HtmlNodeCollection nodes = mcafeeWeb.DocumentNode.SelectNodes(XPATH);
            try
            {
                foreach (HtmlNode node in nodes)
                {
                    try
                    {
                        HtmlAttribute att = node.Attributes["title"];
                        Console.WriteLine(att.Value);
                    }
                    catch
                    {
                        Console.WriteLine("No Value Found");
                    }
                }
            }
            catch
            {
                Console.WriteLine("No Nodes Found.");
            }

I have tried a number of different values for XPATH to find the img including 

"//img[@id='ctl00_mainContent_imgRisk']", which returns no nodes

"//img", which returns some img's but not the correct one

the full XPATH to the img "/html/body[@id='ctl00_MasterBody']/div[@class='wrapper']/div[@class='page']/div[@class='container pageContainer']/div[@class='pageMiddle']/div[@class='pageTopGradient']/div[@class='pageBottomGradient']/div[@class='canvas pageContent pageBannerBolster']/div[@class='row pageBanner pageBannerTeal']/div[@class='area primaryContent']/div[@class='bannerContent bannerContentImage']/img[@id='ctl00_mainContent_imgRisk']", which returns no nodes. 

Does anyone know what I am doing wrong?