This is the complete code:

In the Xaml :

I Have this..

<UserControl x:Class="PMESP.Cofin.Silverlight.PivotGridGeral"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
xmlns:framework="clr-namespace:Infragistics.Samples.Framework;assembly=Infragistics.Samples.Framework"
d:DesignHeight="600" d:DesignWidth="790"
xmlns:ig="http://schemas.infragistics.com/xaml"
xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
xmlns:igOlap="http://schemas.infragistics.com/olap"
xmlns:local="clr-namespace:IGPivotGrid.Samples.Controls"
>
<Grid x:Name="LayoutRoot" Background="White" Margin="10,10,0,0">


<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>

<ig:XamPivotGrid x:Name="pivotGrid"
/>
<ig:Expander Grid.Column="1">
<ig:XamPivotDataSelector x:Name="dataSelector" />
</ig:Expander>

<sdk:Label HorizontalAlignment="Left" Height="19" Margin="10,7,0,0" VerticalAlignment="Top" Width="65" Content="Data Inicial"/>
<ig:XamDateTimeInput x:Name="DataInicial" HorizontalAlignment="Left" Margin="82,5,0,0" VerticalAlignment="Top" Width="95"/>
<sdk:Label HorizontalAlignment="Left" Height="19" Margin="187,7,0,0" VerticalAlignment="Top" Width="60" Content="Data Final"/>
<ig:XamDateTimeInput x:Name="DataFinal" HorizontalAlignment="Left" Margin="254,5,0,0" VerticalAlignment="Top" Width="95"/>
<Button Content="Atualizar" HorizontalAlignment="Left" Margin="357,5,0,0" VerticalAlignment="Top" Width="66" Click="Click_Atualizar"/>
<Button Content="Salvar" HorizontalAlignment="Left" Margin="428,5,0,0" VerticalAlignment="Top" Width="48" Click="Click_Salvar" ToolTipService.ToolTip="Salva customização da consulta"/>
<Button Content="Excel" HorizontalAlignment="Left" Margin="500,5,0,0" VerticalAlignment="Top" Width="48" Click="Click_Excel" ToolTipService.ToolTip="Exportar para planilha excel"/>
</Grid>
</UserControl>

In the Xaml.cs :

public PivotGridGeral()
{
InitializeComponent();
DateTime data = new DateTime(DateTime.Now.Year, 1, 1);
DataInicial.Value = data;
DataFinal.Value = DateTime.Now;
//this.pivotGrid.DataSource.PropertyChanged += DataSource_PropertyChanged;
}
public void CarregarDadosWS(DateTime dataInicial, DateTime dataFinal)
{
wsUPDados.UPdadosClient dados = new wsUPDados.UPdadosClient("BasicHttpBinding_IUPdados");
dados.ConsultaFaturasUPCompleted += new EventHandler<wsUPDados.ConsultaFaturasUPCompletedEventArgs>(dados_CarregarDadosCompleted);
dados.ConsultaFaturasUPAsync(dataInicial, dataFinal);
}
public void dados_CarregarDadosCompleted(Object sender, wsUPDados.ConsultaFaturasUPCompletedEventArgs e)
{
HtmlDocument document = HtmlPage.Document;
HtmlElement elemUge = document.GetElementById("MainContent_hdCodigoUge");
CodUge = elemUge.GetAttribute("value").ToString().Trim();
HtmlElement elemCPF = document.GetElementById("MainContent_hdCPF");
CPF = elemCPF.GetAttribute("value").ToString().Trim();


FlatDataSource DataSource = new FlatDataSource
{
ItemsSource = e.Result

};
CubeMetadata cubeMetadata = new CubeMetadata();
cubeMetadata.DataTypeFullName = "Cubo";
cubeMetadata.DimensionSettings.Add(new DimensionMetadata()
{
SourcePropertyName = "CNPJ",
DisplayName = "CNPJ",
DimensionType = DimensionType.Dimension
});
cubeMetadata.DimensionSettings.Add(new DimensionMetadata()
{
SourcePropertyName = "Codigo_Cliente",
DisplayName = "Codigo Cliente",
DimensionType = DimensionType.Dimension
});
cubeMetadata.DimensionSettings.Add(new DimensionMetadata()
{
SourcePropertyName = "Codigo_Conta",
DisplayName = "Codigo Conta",
DimensionType = DimensionType.Dimension
});
cubeMetadata.DimensionSettings.Add(new DimensionMetadata()
{
SourcePropertyName = "Codigo_Fatura",
DisplayName = "Codigo Factura",
DimensionType = DimensionType.Dimension
});

DataSource.CubesSettings.Add(cubeMetadata);

HierarchyDescriptor dateTimeDescriptor = new HierarchyDescriptor { AppliesToPropertiesOfType = typeof(DateTime) };
dateTimeDescriptor.AddLevel<DateTime>(dt => dt.Year, "Ano");
dateTimeDescriptor.AddLevel<DateTime>(dt => dt.MonthShort(), "Mês");

DataSource.HierarchyDescriptors.Add(dateTimeDescriptor);

this.pivotGrid.DataSource = DataSource;
this.dataSelector.DataSource = DataSource;

DataSource.ParentInFrontForColumns = true;

DataSource.DimensionsGenerationMode = DimensionsGenerationMode.Mixed;

// CarregarCustomizacao();
}

private void Click_Atualizar(object sender, RoutedEventArgs e)
{
DateTime dataInicial = (DateTime)DataInicial.Value;
DateTime dataFinal = (DateTime)DataFinal.Value;
CarregarDadosWS(dataInicial, dataFinal);
}

And this code is the service that returns the list to be loaded into the ItemSource:

public ObservableCollection<BusinessEntities.SL_UP> ConsultaFaturasUP(DateTime DataInicial, DateTime DataFinal)
{
BusinessEntities.SL_UP faturaEntities = new BusinessEntities.SL_UP();
ObservableCollection<BusinessEntities.SL_UP> lista = new ObservableCollection<BusinessEntities.SL_UP>();
Business.SL_UP faturas = new Business.SL_UP();
lista=faturas.ConsultaFaturasUP(DataInicial, DataFinal);
try
{
return lista;
}
catch (Exception excecao)
{
throw new BusinessEntities.Excecao(excecao, id: 1);
}
}

Hopefully this more clear and you can have your help

thank you,