ListView - how to set header to be visible all time

Question

I've ListView inside ScrollViewer. If I scroll listview to bottom the header of listview disappears, how to make it visible constantly?

<Grid HorizontalAlignment="Stretch" VerticalAlignment="Top">
    <ScrollViewer Grid.Row="2" Grid.Column="0">
        <ListView x:Name="cashMagListView"
                              Margin="10"
                              SelectionMode="Single"
                              VirtualizingStackPanel.IsVirtualizing="False">
            <ListView.ItemContainerStyle>
                <Style TargetType="ListViewItem">
                    <Setter Property="Height" Value="35" />
                    <Setter Property="HorizontalContentAlignment" Value="Center" />
                </Style>
            </ListView.ItemContainerStyle>
            <ListView.View>
                <GridView>
                    <GridView.Columns>
                        <GridViewColumn Width="Auto" DisplayMemberBinding="{Binding AutomatNumber, Converter={StaticResource EmptyStringConverter}}" Header="Biletomat" />
                    </GridView.Columns>
                </GridView>
            </ListView.View>
        </ListView>
    </ScrollViewer>
</Grid>