Logical Errors with data binding: a property seems not to update

<Border CornerRadius="10" removed="{Binding SelColor, Mode=OneWay}" BorderBrush="Black" BorderThickness="1" Margin="7">
            <Rectangle MinHeight="20" MinWidth="180" Fill="Transparent" />
        </Border>
        <Expander Header="ChooseColor" Expanded="Expander_Expanded" Name="Exp" Collapsed="Exp_Collapsed">
            <StackPanel>
                <StackPanel Orientation="Horizontal" Margin="2">
                    <TextBlock Text="R" Foreground="{Binding Foreground}"/>
                    <Slider removed="{DynamicResource RedSliderGrad}" Minimum="0" Maximum="255" MinWidth="180" Value="{Binding SelColor.Color.R, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ValueChanged="Slider_ValueChanged"/>
                </StackPanel>
                <StackPanel Orientation="Horizontal" Margin="2">
                    <TextBlock Text="G" Foreground="{Binding Foreground}"/>
                    <Slider removed="{DynamicResource GreenSliderGrad}" Minimum="0" Maximum="255" MinWidth="180" Value="{Binding SelColor.Color.G, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ValueChanged="Slider_ValueChanged"/>
                </StackPanel>
                <StackPanel Orientation="Horizontal" Margin="2">
                    <TextBlock Text="B" Foreground="{Binding Foreground}"/>
                    <Slider removed="{DynamicResource BlueSliderGrad}" Minimum="0" Maximum="255" MinWidth="180" Value="{Binding SelColor.Color.B, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ValueChanged="Slider_ValueChanged"/>
                </StackPanel>
            </StackPanel>
        </Expander>
    </StackPanel>

public SolidColorBrush SelColor
        {
            get { return (SolidColorBrush)GetValue(SelColorProperty); }
            set
            {
                SetValue(SelColorProperty, value);
                if (PropertyChanged != null)
                    PropertyChanged(this, new PropertyChangedEventArgs("SelColor"));
            }
        }

        // Using a DependencyProperty as the backing store for SelColor.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty SelColorProperty =
            DependencyProperty.Register("SelColor", typeof(SolidColorBrush), typeof(ColorChooser), new PropertyMetadata(new SolidColorBrush(Color.FromArgb(255, 204, 204, 204))));

        public ColorChooser()
        {
            InitializeComponent();
            this.DataContext = this;
        }

        private void Expander_Expanded(object sender, RoutedEventArgs e)
        {
            //this.Exp.IsExpanded = true;
            //this.Height += this.Exp.ActualHeight;
        }

        private void Exp_Collapsed(object sender, RoutedEventArgs e)
        {
            //this.Exp.IsExpanded = true;
            //this.Height -= this.Exp.ActualHeight;
            //this.Exp.IsExpanded = false;
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void Slider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
        {

        }