What do you need exactly?

The idea is to show in each stacked bar the quantity of Emission 
for each instalation.In the X we will find the date, and in the Y axis we 
will find the quantity of emissions. 

ValuesOfExcessVSEmissions = 
new ObservableCollection<InstalationEmissionDateInformation>();


public class InstalationEmissionDateInformation
    {
        #region VARIABLES
 
        public string Instalation;
 
        public Decimal Emission;
 
        public string Date;
 
        public Decimal Assignation;
 
        #endregion VARIABLES
 
        public InstalationEmissionDateInformation(string instalation, 
Decimal emission, string date, Decimal assignation)
        {
            Instalation = instalation;
            Emission = emission;
            Date = date;
            Assignation = assignation;
        }
    }

Hi, here's how you could do it:

<UserControl.Resources>
        <local:TestEmissionsCollection x:Key="data" />
        <igChart:GroupBy 
            x:Key="grouped"
            ItemsSource="{StaticResource data}" 
            GroupMemberPath="Date" 
            KeyMemberPath="Installation" 
            ValueMemberPath="Emission" />
    </UserControl.Resources>

    <Grid x:Name="LayoutRoot" Background="White">
        <igChart:XamDataChart x:Name="theChart">
            <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"
                                             >
                   
                </igChart:StackedColumnSeries>
            </igChart:XamDataChart.Series>
        </igChart:XamDataChart>
    </Grid>

And code behind:

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;
        }
    }

Please note that I changed your public fields into properties. This is required, currently.

-Graham

Thank you very much!!

:D

I have another 2 little issues,

I am Working with MVVM and when launching, the graph is painted before the data is got from my BBDD, so, it paints nothing even when I add informations to my Observable collection. I have to do a visibility = visible to the chart to paint my information. Any way of synchronizing this to show directly when my observable collection is created and filled?

The second one is about the legend. How can I show a legend with the name of each installation and it's colour? I want to show a legend and a tooltip when the mouse enters in each bar piece.

Thank you

Do you want a loading splash? Or to hide the chart until there is data? In either case you should just listen to the collectionchanged event on your collection and show the chart or remove the overlaid splash when the data arrives.

You should just be able to point the chart at a legend that you add to the page. Set its legend property. For example, if your legend has a name legend1 then you can do something like this: Legend="{Binding ElementName=legend1}"