How can I change the GradientStops of FastUniformHeatmapRenderableSeries?

Hi, i want to change the GradientStops of FastUniformHeatmapRenderableSeries from ViewModel
Here is the Code below

                    <s:SciChartSurface
                    Width="330"
                    Height="630"
                    s:VisualXcceleratorEngine.EnableImpossibleMode="True"
                    s:VisualXcceleratorEngine.IsEnabled="True"
                    Cursor="Cross">
                    <s:SciChartSurface.RenderableSeries>
                        <s:FastUniformHeatmapRenderableSeries DataSeries="{Binding DataSeries}">
                            <s:FastUniformHeatmapRenderableSeries.ColorMap>
                                <s:HeatmapColorPalette
                                    GradientStops="{Binding ColorMap}"
                                    Maximum="100"
                                    Minimum="0" />
                            </s:FastUniformHeatmapRenderableSeries.ColorMap>
                        </s:FastUniformHeatmapRenderableSeries>
                    </s:SciChartSurface.RenderableSeries>

                    <s:SciChartSurface.XAxis>
                        <s:NumericAxis
                            AxisAlignment="Left"
                            FlipCoordinates="True"
                            Width="30"
                            MajorDelta="60"
                            MinorDelta="20"
                            AutoTicks="True"
                            DrawMajorGridLines="False"
                            DrawMinorGridLines="False"
                            DrawMinorTicks="False"
                            VisibleRange="0, 600" />
                    </s:SciChartSurface.XAxis>
                    <s:SciChartSurface.YAxis>
                        <s:NumericAxis
                            x:Name="YAxis"
                            AxisAlignment="Bottom"
                            FlipCoordinates="True"
                            Height="30"
                            AutoTicks="True"
                            DrawMajorGridLines="False"
                            DrawMinorGridLines="False"
                            DrawMinorTicks="False"
                            MajorDelta="30"
                            MinorDelta="10"
                            VisibleRange="0, 300" />
                    </s:SciChartSurface.YAxis>
                </s:SciChartSurface>

When I change the ColorMap at ViewModel, I can check that GradientStops Property in View is changed. But Chart’s color is not changed.
How can I change the GradientStops of FastUniformHeatmapRenderableSeries from ViewModel ?