I have an ObservableCollection bound to a list box and a boolean property bound to a button. I then defined two converters, one that operates on the collection and the other operates on the boolean property. Whenever I modify the boolean property, the converter's Convert method is called, where as the same is not called if I modify the observable collection. What am I missing??

Snippets for your reference,

xaml snipet,

<Window.Resources>
    <local:WrapPanelWidthConverter x:Key="WrapPanelWidthConverter" />
    <local:StateToColorConverter x:Key="StateToColorConverter" />
</Window.Resources>
<StackPanel>
    <ListBox x:Name="NamesListBox" ItemsSource="{Binding Path=Names}">
        <ListBox.ItemsPanel>
            <ItemsPanelTemplate>
                <WrapPanel x:Name="ItemWrapPanel" Width="500" Background="Gray">
                    <WrapPanel.RenderTransform>
                        <TranslateTransform x:Name="WrapPanelTranslatation" X="0" />
                    </WrapPanel.RenderTransform>
                    <WrapPanel.Triggers>
                        <EventTrigger RoutedEvent="WrapPanel.Loaded">
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation Storyboard.TargetName="WrapPanelTranslatation" Storyboard.TargetProperty="X" To="{Binding Path=Names,Converter={StaticResource WrapPanelWidthConverter}}" From="525"  Duration="0:0:2" RepeatBehavior="100" />
                                </Storyboard>
                            </BeginStoryboard>
                        </EventTrigger>
                    </WrapPanel.Triggers>
                </WrapPanel>
            </ItemsPanelTemplate>
        </ListBox.ItemsPanel>
        <ListBox.ItemTemplate>
            <DataTemplate>
                <Grid>
                    <Label Content="{Binding}" Width="50" Background="LightGray" />
                </Grid>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
    <Button Content="{Binding Path=State}" Background="{Binding Path=State, Converter={StaticResource StateToColorConverter}}" Width="100" Height="100" Click="Button_Click" />
</StackPanel>   

code behind snippet

public class WrapPanelWidthConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        ObservableCollection<string> aNames = value as ObservableCollection<string>;
        return -(aNames.Count * 50);
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}


public class StateToColorConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        bool aState = (bool)value;
        if (aState)
            return Brushes.Green;
        else
            return Brushes.Red;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}