C#

System.NullReferenceException was unhandled<br />
  Message="Object reference not set to an instance of an object."<br />
  Source="System.Windows.Forms"

public void zap_publish_listview(zap item)<br />
        {<br />
            if (listView_main.InvokeRequired)<br />
            {<br />
                SetZapPublishListview s = new SetZapPublishListview(zap_publish_listview);<br />
                Invoke(s, new object[] { item });<br />
            }<br />
            else<br />
            {<br />
                // Extract data from zap item<br />
                int icon = getStatusIconNumber(item.zap_state.ToString());<br />
                string name = item.zap_channel.ToString();<br />
                string data = item.zap_state.ToString();<br />
<br />
                // Create listview item<br />
                ListViewItem lvItem = new ListViewItem("", icon);<br />
                lvItem.SubItems.Add("ZAP: " + name);<br />
                lvItem.SubItems.Add(data);<br />
                lvItem.ToolTipText = item.ToString();<br />
                lvItem.Group = listView_main.Groups[2]; // ZAP group is index 2<br />
<br />
                // Find location of listview item to be replaced<br />
                ListViewItem old_item = listView_main.FindItemWithText("ZAP: " + name, true, 0);<br />
<br />
                // If item exists<br />
                if (old_item.Index >= 0)<br />
                {<br />
                    // Insert listview item<br />
                    listView_main.Items.Insert(old_item.Index, lvItem);<br />
<br />
                    // Remove old item<br />
                    listView_main.Items.RemoveAt(old_item.Index);<br />
                }<br />
                else<br />
                {<br />
                    // Insert listview item<br />
                    listView_main.Items.AddRange(new ListViewItem[] { lvItem });<br />
                }<br />
            }<br />
        }<br />