网格包装的WPF DataGrid不会水平滚动

当窗口太小而无法显示所有列时,我试图使DataGrid水平滚动。我使用网格来控制元素的位置。有人能解释为什么滚动条没有出现,以及我如何修复它吗?如果可能的话,我更喜欢仅XAML的解决方案。

这是我的完整代码。你可以随意评论你看到的任何奇怪的东西,因为我是WPF的新手。

<Window x:Class="FBLAM.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:FBLAM"
    mc:Ignorable="d"
    Title="MainWindow" Width="800" Height="600">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>
    <Menu Grid.Row="0" Grid.Column="0" IsMainMenu="True" Height="20" VerticalAlignment="Top">
        Menu Goes Here
    </Menu>
    <Grid Grid.Row="1" Grid.Column="0" HorizontalAlignment="Center" Background="#FFF0F0F0">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <StackPanel Grid.Column="1" Grid.Row="0" Orientation="Horizontal" VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
            <Button Content="Button1" HorizontalAlignment="Left" Padding="10,2" VerticalAlignment="Center"/>
            <Button Content="Button2" HorizontalAlignment="Left" Padding="10,2" VerticalAlignment="Center" Margin="10,0,0,0"/>
        </StackPanel>
        <DataGrid 
              Grid.Column="1" 
              Grid.Row="1" 
              x:Name="MemberData" 
              AutoGenerateColumns="False" 
              IsReadOnly="False" 
              CanUserResizeColumns="True" 
              CanUserAddRows="True" 
              CanUserSortColumns="True" 
              ItemsSource="{Binding}" 
              SelectionMode="Single" 
              HeadersVisibility="Column" 
              HorizontalContentAlignment="Stretch" 
              VerticalContentAlignment="Stretch" 
              BorderThickness="0" 
              Margin="0" 
              GridLinesVisibility="Horizontal"
              ScrollViewer.CanContentScroll="True" 
              ScrollViewer.HorizontalScrollBarVisibility="Visible">
            <DataGrid.Columns>
                <DataGridTextColumn Header="ID" Binding="{Binding Id}" />
                <DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" />
                <DataGridTextColumn Header="Last Name" Binding="{Binding LastName}" />
                <DataGridTextColumn Header="School" Binding="{Binding School}" />
                <DataGridTextColumn Header="State" Binding="{Binding State}" />
                <DataGridHyperlinkColumn Header="Email" Binding="{Binding Email}" />
                <DataGridTextColumn Header="Year Joined" Binding="{Binding YearJoined}" />
                <DataGridTextColumn Header="Grade" Binding="{Binding Grade}" />
                <DataGridCheckBoxColumn Header="Active" Binding="{Binding Active}" />
                <DataGridTextColumn Header="Amount Owed" Binding="{Binding AmountOwed, StringFormat=C}" />
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Grid>