get all selected items from wpf checkbox list give me error

I have listbox with checked box as following, & it binding its data from sql server database,
, I want to get selected items value When I run this but I got this error
 
Unable to cast object of type 'System.Data.DataRowView' to type 'System.Windows.Controls.CheckBox'.

<Window.Resources><DataTemplate x:Key="NameColumnTemplate"><CheckBox Height="20"  FontFamily="Arial" FontSize="14"  Content="{Binding Path=PermissionDescription}" 
                      Tag="{Binding PermissionID}" HorizontalAlignment="Stretch" VerticalAlignment="Center"
                      /></DataTemplate></Window.Resources><Grid><ListBox HorizontalAlignment="Stretch" Margin="12,12,136,21" Name="lstEmployees" 
                          VerticalAlignment="Stretch" ItemsSource="{Binding Tables[0]}"  
                          ItemTemplate="{StaticResource NameColumnTemplate}" 
                          ScrollViewer.VerticalScrollBarVisibility="Auto" removed="{x:Null}" 
                         BorderBrush="#FFAD7F30"  
                 SelectionChanged="lst_SelectionChanged" CheckBox.Click="lst_SelectionChanged"/><Button Content="listbox" Height="23" HorizontalAlignment="Left" Margin="214,207,0,0" Name="btnShowSelectedItems" 
                VerticalAlignment="Top" Width="75" Click="btnShowSelectedItems_Click" /></Grid>

public Window2()
        {
            InitializeComponent();
            // bind data 
            lstEmployees.DataContext = SelJobsCat();
        }
 
 private void btnShowSelectedItems_Click(object sender, RoutedEventArgs e)
        {
            foreach (CheckBox item in lstEmployees.Items)
            {
                if (item.IsChecked == true)
                {
                    System.Windows.MessageBox.Show((item.Content + " is checked."));
                }
            }
        }
        private void lst_SelectionChanged(object sender, RoutedEventArgs e)
        {
            if (e.OriginalSource is CheckBox)
            {
                lstEmployees.SelectedItem = e.OriginalSource;
            }
            if (lstEmployees.SelectedItem == null) return;
            Console.WriteLine(lstEmployees.SelectedIndex);
            Console.WriteLine(((CheckBox)lstEmployees.SelectedItem).IsChecked);
        }