SelectListItem of MultiCombo not working

[Rupesh]

Dear Sir,

I am using MultiCombo control. Here is the code.

<ext:MultiCombo ID="MultiCombo1" runat="server" Width="260">
            <Items>
                <ext:ListItem Text="Item 1" Value="1" />
                <ext:ListItem Text="Item 2" Value="2" />
                <ext:ListItem Text="Item 3" Value="3" />
                <ext:ListItem Text="Item 4" Value="4" />
                <ext:ListItem Text="Item 5" Value="5" />
            </Items>
            </ext:MultiCombo>

                <ext:Button runat="server" ID="btnSave" Text="Save">
                    <DirectEvents>
                        <Click OnEvent="GetData"></Click>
                    </DirectEvents>
                </ext:Button>

On button click I am trying to set selected values.

  protected void GetData(object sender, DirectEventArgs e)
    {
        MultiCombo1.SelectedItems.Add(new SelectedListItem("2"));
        //MultiCombo1.Render();
    }

But After button click no items are selected.
when I add MultiCombo1.Render(); line I can see the combo with selected records but there are two combo one with selected records and one with empty text record.

please guide me.

Thanks
Rupesh