private void ComboBox_DropDownClosed(object sender, EventArgs e) { string s = comboBox1.Text; ComboBox cmb = sender as ComboBox; if (s != "Make Selection...") { InspectionService inspectionService = new InspectionService(); var Manholes = inspectionService.GetManholeByDrainageArea(s); List <Author> authors = new List <Author>(); foreach (var manhole in Manholes) { authors.Add(new Author() { Manhole = manhole }); } dataGrid1.ItemsSource = authors; } else { dataGrid1.ItemsSource = null; } }