private void cbModel_SelectedIndexChanged(object sender, EventArgs e) { cbType.Text = ""; try { cbType.Items.Clear(); if (cbModel.SelectedIndex.ToString() != "") { List <string> modelNumbers = CC.GetModelNumbers(cbModel.SelectedItem.ToString()); cbType.Items.Add(""); foreach (string s in modelNumbers) { cbType.Items.Add(s); } } } catch (Exception) { MessageBox.Show("Connection error"); } }