To reproduce:

- add a RadDropDownList , MS ComboBox and a RadButton;

Use the following code:

public partial class Form1 : Form { private List<States> stateslist = new List<States>(); private BindingSource addressBindingSource = new BindingSource(); private BindingSource statesBindingSource = new BindingSource(); public Form1() { InitializeComponent(); addressBindingSource.DataSource = typeof(Address); statesBindingSource.DataSource = typeof(States); stateslist.Add(new States { DisplayName = "California", ID = 1 }); stateslist.Add(new States { DisplayName = "Nevada", ID = 2 }); stateslist.Add(new States { DisplayName = "New York", ID = 1 }); statesBindingSource.DataSource = stateslist; this.radDropDownList1.DataBindings.Add(new System.Windows.Forms.Binding("SelectedValue",addressBindingSource, "State_ID", true)); this.radDropDownList1.DataSource = statesBindingSource; this.radDropDownList1.DisplayMember = "DisplayName"; this.radDropDownList1.ValueMember = "ID"; this.radDropDownList1.DropDownStyle = Telerik.WinControls.RadDropDownStyle.DropDownList; this.comboBox1.DataBindings.Add(new System.Windows.Forms.Binding("SelectedValue", addressBindingSource, "State_ID", true)); this.comboBox1.DataSource = statesBindingSource; this.comboBox1.DisplayMember = "DisplayName"; this.comboBox1.ValueMember = "ID"; this.comboBox1.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList; } private void radButton1_Click(object sender, EventArgs e) { Address newEntity = new Address(); addressBindingSource.DataSource = newEntity; } } public class States { public int ID { get; set; } public string DisplayName { get; set; } } public class Address { public string Address1 { get; set; } public string Address2 { get; set; } public string ZipCode { get; set; } public int State_ID { get; set; } } 1. Select an item from either the dropdownlist or the combobox. 2. Click the button. At this point both the dropdownlist and combobox controls would clear themselves. 3. Select an item again from either the dropdownlist or the combobox. 4. Click the button again. At this point only the .NET combobox will clear while the Telerik dropdownlist will retain the displayed item.

Workaround:

add an empty State in the stateslist:

stateslist.Add(new States() {DisplayName = "", ID = 0});