Chart in datatemplate not working

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Silverlight

I have created a listbox with an itemtemplate that contains a chart. My problem is that the my columnseries dependent and independent values doesn't seem to bind.

<DataTemplate x:Key="Template">
    <StackPanel HorizontalAlignment="Left">
        <toolkit:Chart Title="{Binding ID}" LegendStyle="{StaticResource LegendStyleNoBackground}" Padding="5" BorderThickness="0" Height="500" Width="800">
            <toolkit:ColumnSeries ItemsSource="{Binding}" DependentValuePath="m1_percent" IndependentValuePath="m1_period" Title="{Binding m1_period}" />
        </toolkit:Chart>
    </StackPanel>
</DataTemplate>

The databinding on chart title and columnseries title works, but not the dependent and independent value. i have checked m1_peroid, m1_percent that it's the correct name of the property.

Any ideas?