Custom Column Chart Datapoint in Silverlight.

                          <TextBlock  Text="{TemplateBinding FormattedIndependentValue}"  FontWeight="Bold"  Margin="0,-20,0,0" VerticalAlignment="Bottom"   HorizontalAlignment="Center" />

                      </Grid>
                  </ControlTemplate>
              </Setter.Value>
          </Setter>
      </Style>

In Code Behind:

line.DataPointStyle = (Style)Resources["DataPointStyle1"];