Hi, I am trying to set the selected value of a combobox from a style trigger.It works as long as we dont manually change any value in the combobox.But it stops working altogether after manually changing the selection.How can i solve this.A sample code is attached.Please do help

<Window x:Class="InputGesture.Window2"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:InputGesture"
    Title="Window2" Height="300" Width="300" Name="Sample">
    <Window.Resources>
        <Style TargetType="{x:Type ComboBox}">
            <Setter Property="ComboBox.SelectedValue" Value="1"/>
            <Style.Triggers>
                <DataTrigger Binding="{Binding ElementName=chk,Path=IsChecked}" Value="True">
                    <Setter Property="ComboBox.IsEnabled" Value="False"/>
                    <Setter Property="ComboBox.SelectedValue" Value="2"/>
                </DataTrigger>
            </Style.Triggers>
            </Style>
    </Window.Resources>
    <StackPanel>
        <CheckBox Name="chk" Height="23"/>
        <ComboBox Name="cmb" Height="23" DisplayMemberPath="Name"             
                  SelectedValuePath="Id" ItemsSource="{Binding ElementName=Sample,Path=DT}">
        </ComboBox>

        <Button Height="23" Click="Button_Click"/>
    </StackPanel>
</Window>