What do you need exactly?

Looks like there is a bit of a functionality hole there for the auto generated case. I couldn't find a straightforward way to make the series title equal the key for that series.
So you may want to make a feature request. But you can do the below to work around the missing functionality.

<UserControl.Resources>
        <local:TestEmissionsCollection x:Key="data" />
        <igChart:GroupBy 
            x:Key="grouped"
            ItemsSource="{StaticResource data}" 
            GroupMemberPath="Date" 
            KeyMemberPath="Installation" 
            ValueMemberPath="Emission" />
        
        <local:KeyConverter x:Key="keyConverter" />
        
        <DataTemplate x:Key="keyLegendItemTemplate">
            <StackPanel Orientation="Horizontal" Margin="1" Visibility="{Binding Series.Visibility}">
                <ContentPresenter Content="{Binding}" ContentTemplate="{Binding Series.LegendItemBadgeTemplate}" />
                <ContentPresenter Content="{Binding Series.ValueMemberPath, Converter={StaticResource keyConverter}, ConverterParameter='_Emission'}"/>
            </StackPanel>
        </DataTemplate>
    </UserControl.Resources>

    <Grid x:Name="LayoutRoot" Background="White">
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition Width="Auto" />
        </Grid.ColumnDefinitions>
        <igChart:XamDataChart x:Name="theChart"
                              Legend="{Binding ElementName=legend1}">
            <igChart:XamDataChart.Axes>
                <igChart:CategoryXAxis x:Name="xAxis" 
                                       ItemsSource="{StaticResource grouped}"
                                       Label="{}{Key}"/>
                <igChart:NumericYAxis x:Name="yAxis" />
            </igChart:XamDataChart.Axes>

            <igChart:XamDataChart.Series>
                <igChart:StackedColumnSeries x:Name="stack"
                                             ItemsSource="{StaticResource grouped}"
                                             XAxis="{Binding ElementName=xAxis}"
                                             YAxis="{Binding ElementName=yAxis}"
                                             AutoGenerateSeries="True"
                                             LegendItemTemplate="{StaticResource keyLegendItemTemplate}"
                                             >
                   
                </igChart:StackedColumnSeries>
            </igChart:XamDataChart.Series>
        </igChart:XamDataChart>
        
        <igChart:Legend x:Name="legend1" Grid.Column="1" />
    </Grid>
</UserControl>

And code behind:

 public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();
        }
    }

    public class TestEmissionsCollection
        : ObservableCollection<InstalationEmissionDateInformation>
    {
        public TestEmissionsCollection()
        {
            Add(new InstalationEmissionDateInformation("A", 5, "1/1/2012", 1));
            Add(new InstalationEmissionDateInformation("B", 2, "1/1/2012", 1));
            Add(new InstalationEmissionDateInformation("C", 7, "1/1/2012", 1));
            Add(new InstalationEmissionDateInformation("A", 6, "1/2/2012", 1));
            Add(new InstalationEmissionDateInformation("B", 3, "1/2/2012", 1));
            Add(new InstalationEmissionDateInformation("C", 8, "1/2/2012", 1));
            Add(new InstalationEmissionDateInformation("A", 6, "1/3/2012", 1));
            Add(new InstalationEmissionDateInformation("B", 3, "1/3/2012", 1));
            Add(new InstalationEmissionDateInformation("C", 6, "1/3/2012", 1));
            Add(new InstalationEmissionDateInformation("A", 4, "1/4/2012", 1));
            Add(new InstalationEmissionDateInformation("B", 3, "1/4/2012", 1));
            Add(new InstalationEmissionDateInformation("C", 7, "1/4/2012", 1));
        }
    }

    public class InstalationEmissionDateInformation
    {
        public string Installation { get; set; }
        public Decimal Emission { get; set; }
        public string Date { get; set; }
        public Decimal Assignation { get; set; }

        public InstalationEmissionDateInformation(
            string installation, 
            Decimal emission, 
            string date, 
            Decimal assignation)
        {
            Installation = installation;
            Emission = emission;
            Date = date;
            Assignation = assignation;
        }
    }

    public class KeyConverter
        : IValueConverter
    {

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (value is string && parameter is string)
            {
                var key = (string)value;
                var param = (string)parameter;

                key = key.Replace(param, "");

                return key;
            }

            return "";
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

Hope this helps!
-Graham

There is no luck, it shows "Series Title".

By the way, I am getting a problem that I have posted in this forum, that when I ask my server to change the data to show, it does not paint any bar, and I have realized that the legend neither changes. I know this because it must show 4 elements when I change my detail option and it continues showing 6 of my default choice.

Did you properly merge in all the changes from the sample I posted? It sounds like you are not setting the LegendItemTemplate

-Graham

no luck

If you run the code I posted you will see it has the expected behavior. Are you still seeing "Series Title"? Can you post a sample project that exhibits the behavior you are seeing?

I have the latest version, so I will be waiting for it, thank you.

By the way and trying to show something clear to my costumer, I have introduced a tooltip.

I am trying to show the name and the value of each column and I have just achieved to show the name. While trying to bind to the KeyMemberPath it shows in the output a binding error that tells the inexistence of such property in the series. My xaml code for your example:

ig:StackedColumnSeries.ToolTip>
     <StackPanel Orientation="Vertical">
           <StackPanel Orientation="Horizontal">
               <ContentPresenter Content="{Binding Series.KeyMemberPath,
                    Converter={StaticResource keyConverter},
                    ConverterParameter='_Total'}"/>
           </StackPanel>
 
           <Rectangle Fill="Aquamarine"  Height="1" Stretch="Fill" 

                 Margin="4"/>
           <StackPanel Orientation="Horizontal">
                <ContentPresenter Content="{Binding Series.ValueMemberPath,
                          Converter={StaticResource keyConverter},
                          ConverterParameter='_Emission'}"
                          Width="Auto" />
           </StackPanel>
    </StackPanel>
</ig:StackedColumnSeries.ToolTip>

I believe you are hitting a bug with the initial version of 11.2. I would recommend updating to the most recent service release. And if that doesn't fix the issue, then it should be in the next available service release, which should be quite soon.

-Graham

It seems that it does not take the data template, because it doesn't debug the converter and even if I put a simple textblock instead of the content panel it continues showing the same in the legend

The version of my xamDataChart for silverlight 5  is 11.2.20112.45.

Thank you