TreeView search

This function find only first node in treeview, that contains SearchText.

private TreeNode SearchNode(string SearchText,TreeNode StartNode)
{
    TreeNode node=null;
    while (StartNode!= null)
    {
        if (StartNode.Text.ToLower().Contains(SearchText.ToLower()))
        {
            node = StartNode; 
            break;
        };
        if (StartNode.Nodes.Count != 0) 
        {
            node=SearchNode(SearchText, StartNode.Nodes[0]);//Recursive Search
            if (node != null)
            {
                break;
            };
        };
        StartNode = StartNode.NextNode;
    };
    return node;
} 

private void button1_Click(object sender, EventArgs e)
{
    string SearchText = this.textBox1.Text;
    if (SearchText == "")
    {
        return;
    };
    TreeNode SelectedNode = SearchNode(SearchText, treeView1.Nodes[0]);
    if (SelectedNode != null)
    {
        this.treeView1.SelectedNode = SelectedNode;
        this.treeView1.SelectedNode.Expand();
        this.treeView1.Select();
    };
}

How should I change it, so the function will able to find not only the first node, but all of them, every time when I click button1, it'll find next node till the end, and then it starts from the beginning? So I should search not from TreeView1.Nodes[0], but from TreeView1.SelectedNode...