Getting a String from a TreeView

Hello, I have been trying some code on how to get a String from a TreeView. The String would have all The TreeNodes with a "\n" in between each one. It is irrelevant which order the TreeNodes are in. Here is some of my code...

        private void button1_Click(object sender, EventArgs e)
        {
            String str = "";

            for (int i = 0; i < lstTiles.Nodes.Count; i++)
            {
                TreeNode node = lstTiles.Nodes[i];
                String addon = getStringFromNode(node);
                if (addon != "")
                {
                    str += "\n" + addon;
                }

                if (i != lstTiles.Nodes.Count - 1)
                {
                    str += "\n";
                }
            }
            Clipboard.SetText(str);
        }

        private String getStringFromNode(TreeNode nodes)
        {
            String str = "";

            for (int i = 0; i < nodes.Nodes.Count; i++)
            {
                TreeNode node = nodes.Nodes[i];
                str += node.Text;
                String addon = getStringFromNode(node);
                if (addon != "")
                {
                    str += "\n" + addon;
                }

                if (i != lstTiles.Nodes.Count - 1)
                {
                    str += "\n";
                }
            }

            return str;
        }

Any ideas why this isn't working?