Silverlight checkbox two way binding does not work as expected

I have a simple issue setting a two way checkbox binding in Silverlight 3.0. It must be tricky, but maybe I forgot my brain today ...

I have defined a Model class to represent my ... data. I have implemented the INotifyPropertyChanged interface so that the UI can see when the data changes.

public class Model : INotifyPropertyChanged
{
    private bool _value;
    public bool Value
    {
        get { return this._value; }
        set
        {
            if (this.PropertyChanged != null)
                this.PropertyChanged(this, new PropertyChangedEventArgs("Value"));
            this._value = value;
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

      

        
        
        
      

    

Then I'll put a checkbox and a button on .. 'form':

    <StackPanel Orientation="Horizontal">
        <CheckBox x:Name="check" IsChecked="{Binding Value, Mode=TwoWay}" Content="SomeLabel"/>    
        <Button Click="Button_Click" Content="Test" />
    </StackPanel>

      

        
        
        
      

    

Then I provided the data in the constructor:

    public MainPage()
    {
        InitializeComponent();

        this.DataContext = new Model() { Value = true };
    }

      

        
        
        
      

    

The problem is that you need to double click on the checkbox to check / uncheck the checkbox, unless I uninstall INotifyPropertyChanged. However, if he uninstalls it, the UI won't notice if the underlying data changes.

If I remove the Mode = TwoWay bit from the IsChecked binding expression, then also the UI won't notice the underlying data change, even if the model implements the interface.

How to do:

• Check the box data bound on startup
• Check the Fixed box to change the underlying data.
• Check the box to define baseline changes and data updates?