Listbox not scrolling if inside HeaderedContentControl

Question

Hi, I can get the listbox to scroll, I have my listbox inside a headredContentControl. Below is my code:

<UserControl x:Class="SilverlightApplication1.Views.xx"
    xmlns:toolkit="http://schemas.microsoft.com/winfx/2006/xaml/presentation/toolkit"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
   >
        <Grid x:Name="LayoutRootMain" >
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto" />
                <RowDefinition Height="Auto" />
                <RowDefinition Height="Auto" />
            </Grid.RowDefinitions>
                <toolkit:HeaderedContentControl Grid.Row="0" FontSize="12" Width="700" 
                                                Margin="60" 
                                                Header="Header Title">
            <ListBox Name="EmployeeListBox" Background="Transparent" Margin="40" Grid.Row="0"
                                 SelectionMode="Single"
                                 ItemsSource="{Binding Employees, Mode=TwoWay}"  >
                <ListBox.ItemTemplate>
                    <DataTemplate >
                        <StackPanel>
                            <Grid>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="120" />
                                    <ColumnDefinition Width="140" />
                                </Grid.ColumnDefinitions>
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                </Grid.RowDefinitions>
                                <TextBlock  Grid.Column="0" Grid.Row="0" FontWeight="Bold" Text="Name:" />
                                <TextBlock x:Name="TextBlock1"  Grid.Column="1" Grid.Row="0"  
                                           Text="{Binding Name}" />
                            </Grid>
                        </StackPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
        </toolkit:HeaderedContentControl>
        </Grid>
</UserControl>