WPF DataGrid + radiobutton problems

<Window.Resources>
        <XmlDataProvider x:Key="XmlData" Source="limits.xml"/>
        <DataTemplate x:Key="CustomCapacityTemplate">
            <StackPanel>
                <TextBlock Text="{Binding XPath=title}" FontWeight="Bold" Margin="10" />
                <TextBlock Text="{Binding XPath=description}" Margin="10 0" />
            </StackPanel>
        </DataTemplate>
        <local:EnumMatchToBooleanConverter x:Key="enumConverter" />
    </Window.Resources>
...
<DataGrid AutoGenerateColumns="False" VerticalAlignment="Stretch"  Grid.Row="1" Name="dg1" ItemsSource="{Binding Source={StaticResource XmlData},XPath=Limits/*}">
                <DataGrid.Columns>
                    <DataGridTemplateColumn Header="Capacité" CellTemplate="{StaticResource CustomCapacityTemplate}" />
                    <DataGridTemplateColumn Header="Aucune" Width="60">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <RadioButton GroupName="{Binding XPath=ID}" IsChecked="{Binding Path=CurrentOption, Mode=TwoWay, Converter={StaticResource enumConverter}, ConverterParameter=Aucune}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn Header="Légère" Width="60">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <RadioButton GroupName="{Binding XPath=ID}" IsChecked="{Binding Path=CurrentOption, Mode=TwoWay, Converter={StaticResource enumConverter}, ConverterParameter=Légère}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn Header="Modérée" Width="60">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <RadioButton GroupName="{Binding XPath=ID}" IsChecked="{Binding Path=CurrentOption, Mode=TwoWay, Converter={StaticResource enumConverter}, ConverterParameter=Modérée}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn Header="Forte" Width="60">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <RadioButton GroupName="{Binding XPath=ID}" IsChecked="{Binding Path=CurrentOption, Mode=TwoWay, Converter={StaticResource enumConverter}, ConverterParameter=Forte}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn Header="Totale" Width="60">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <RadioButton GroupName="{Binding XPath=ID}" IsChecked="{Binding Path=CurrentOption, Mode=TwoWay, Converter={StaticResource enumConverter}, ConverterParameter=Totale}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
                
                <DataGrid.RowDetailsTemplate>
                    <DataTemplate>
                        <StackPanel>
                            <TextBlock Text="{Binding XPath=explicationTitle}" FontWeight="Bold" Margin="10" />
                            <TextBlock Text="{Binding XPath=explicationDescription}" Margin="10" />
                            <TextBlock Text="Aucune" FontWeight="Bold" Margin="10" />
                            <TextBlock Text="{Binding XPath=explicationLimiteAucune}" Margin="10" />
                            <TextBlock Text="Modérée" FontWeight="Bold" Margin="10" />
                            <TextBlock Text="{Binding XPath=explicationLimiteModeree}" Margin="10" />
                            <TextBlock Text="Totale" FontWeight="Bold" Margin="10" />
                            <TextBlock Text="{Binding XPath=explicationLimiteTotale}" Margin="10" />
                        </StackPanel>
                    </DataTemplate>
                </DataGrid.RowDetailsTemplate>
            </DataGrid>

using System;
using System.Globalization;
using System.Windows.Data;

namespace ICF_Form
{
    class EnumMatchToBooleanConverter : IValueConverter
    {
        public object Convert(object value, Type targetType,
                              object parameter, CultureInfo culture)
        {
            if (value == null || parameter == null)
                return false;

            string checkValue = value.ToString();
            string targetValue = parameter.ToString();
            return checkValue.Equals(targetValue,
                     StringComparison.InvariantCultureIgnoreCase);
        }

        public object ConvertBack(object value, Type targetType,
                                  object parameter, CultureInfo culture)
        {
            if (value == null || parameter == null)
                return null;

            bool useValue = (bool)value;
            string targetValue = parameter.ToString();
            if (useValue)
                return Enum.Parse(targetType, targetValue);

            return null;
        }
    }
}