A value of type 'LineSeries' cannot be added to a collection or dictionary of type 'Collection`1'

Jun 10, 2015 at 1:30 PM
Hello there, I'm building an Universal App and I'm using this toolkit, in particular to display charts.
I'm having this seriously annoying issue in which the XAML designer reports an error, but compiles and executes OK.
The error is the one in the title:
A value of type 'LineSeries' cannot be added to a collection or dictionary of type 'Collection`1'.

This is reported for all series classes in any chart.

My XAML is as follows:

...
xmlns:charting="using:WinRTXamlToolkit.Controls.DataVisualization.Charting"
xmlns:Series="using:WinRTXamlToolkit.Controls.DataVisualization.Charting"

...
<charting:Chart x:Name="LineChart" Width="800" Height="600" Title="Evolución del balance" >
                        <charting:Chart.Series>
                            <Series:LineSeries
                                 Title="Circulante" Margin="0" 
                                             IndependentValueBinding="{Binding Key}" DependentValueBinding="{Binding Value}" IsSelectionEnabled="False" 
                                             ItemsSource="{Binding EvolucionCirculante, Mode=OneWay}" />
                            <Series:LineSeries Title="Largo" Margin="0" 
                                             IndependentValueBinding="{Binding Key}" DependentValueBinding="{Binding Value}" IsSelectionEnabled="False" 
                                             ItemsSource="{Binding EvolucionLargo, Mode=OneWay}" />
                            <Series:LineSeries Title="Activo Fuera Balance" Margin="0" 
                                             IndependentValueBinding="{Binding Key}" DependentValueBinding="{Binding Value}" IsSelectionEnabled="False" 
                                             ItemsSource="{Binding EvolucionActivoFueraBalance, Mode=OneWay}" />
                            <Series:LineSeries Title="Captación Balance" Margin="0" 
                                             IndependentValueBinding="{Binding Key}" DependentValueBinding="{Binding Value}" IsSelectionEnabled="False" 
                                             ItemsSource="{Binding EvolucionCaptacionBalance, Mode=OneWay}" />
                            <Series:LineSeries Title="Captación Fuera Balance" Margin="0" 
                                             IndependentValueBinding="{Binding Key}" DependentValueBinding="{Binding Value}" IsSelectionEnabled="False" 
                                             ItemsSource="{Binding EvolucionCaptacionFueraBalance}" />
                        </charting:Chart.Series>

                    </charting:Chart>
As I said, this error is raised only on the XAML designer, not during compilation or runtime, but it's VERY annoying, especially because I'm left without intellisense on the Series node.

I reviewed the sample, and looks pretty much the same as mine, I'm clueless, any help is appreciated.