How to add custom tooltip to SL PieChart {IN CODE}

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C#

Silverlight

chart

Hi.

I need add custum tooltip to my pie chart in code .

My (not working) code :

ResourceDictionaryCollection palette = new ResourceDictionaryCollection();
for (int i = 0; i < pieChart.Colors; i++)
{
Style style = new Style(typeof(Control));
style.Setters.Add(new Setter(BackgroundProperty,GetColorFromHexa(pieChart.Colors[i])));
ResourceDictionary dictionary = new ResourceDictionary();
Style styleTT = new Style(typeof(ToolTip));
styleTT.Setters.Add(new Setter(ContentControl.ContentProperty, "Custom ToolTip"));
styleTT.Setters.Add(new Setter(ContentControl.ContentProperty,"{TemplateBinding FormattedDependentValue}"));
styleTT.Setters.Add(new Setter(ContentControl.ContentProperty,"{TemplateBinding FormattedRatio}"));
styleTT.Setters.Add(new Setter(ContentControl.ContentProperty, "{Binding Key}"));
ToolTip tt = new ToolTip();
tt.Style = styleTT;
style.Setters.Add(new Setter(ToolTipService.ToolTipProperty,tt));
dictionary.Add("DataPointStyle", style);
palette.Add(dictionary);
}
((PieSeries)graf.Series[0]).Palette = palette;

Colors work fine but tooltip is not working.

P.S.: do not post XAML code pls, its not solution for me. THX