I do not understand why the error ! :S

[C# Programming]

private void Action(int ust_id) { MySqlCommand cmd = new MySqlCommand("Select * From kategoriler_tablo Where UstKategoriId=" + ust_id.ToString(), c); c.Open(); MySqlDataReader r = cmd.ExecuteReader(); while (r.Read()) { if (ust_id != 0) { treeView1.Nodes.Find(ust_id.ToString(), true)(0).Nodes.Add(r("id").ToString(), r("KategoriAdi").ToString()); } else { treeView1.Nodes.Add(r("id").ToString(), r("KategoriAdi").ToString()); } Action(Convert.ToInt32(r("id"))); } r.Close(); c.Close() } private void Button1_Click(System.Object sender, System.EventArgs e) { if (c.State != ConnectionState.Open) { } TreeView1.Nodes.Clear(); TreeView1.Update(); c.close(); Action(0); }

This code does not work. I could not understand where the fault is
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