Не могу обратится к ListBox С# MVVM WPF

Цель - сделать отчет в CSV файл.

3 папки:

• Models
  Human.cs
• Viewmodels
  HumanViewModel.cs
• Views
  MainWindow.xaml

Human

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;
namespace Tutorial_Wpf_MVVM.Models
{
    class Human : INotifyPropertyChanged
    {
        private string _firstname;
        private string _surname;
        private string _passport;
        private string _databirth;
        public string FirstName
        {
            get
            {
                return _firstname;
            }
            set
            {
                _firstname = value;
                OnPropertyChanged("FirstName");
            }
        }
        public string Surname
        {
            get
            {
                return _surname;
            }
            set
            {
                _surname = value;
                OnPropertyChanged("Surname");
            }
        }
        public string Passport
        {
            get
            {
                return _passport;
            }
            set
            {
                _passport = value;
                OnPropertyChanged("Passport");
            }
        }
        public string Databirth
        {
            get
            {
                return _databirth;
            }
            set
            {
                _databirth = value;
                OnPropertyChanged("Databirth");
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged([CallerMemberName]string prop = "")
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(prop));
        }
    }
}

HumanViewModel

class HumansViewModel : INotifyPropertyChanged
    {
        private Human _selectedhuman;
        public ObservableCollection<Human> Humans { get; set; }
        public Human SelectedHuman
        {
            get { return _selectedhuman; }
            set
            {
                _selectedhuman = value;
                OnPropertyChanged("SelectedHuman");
            }
        }
        public HumansViewModel()
        {
            Humans = new ObservableCollection<Human>
        {
            new Human { FirstName="Иван", Surname="Иванов", Passport="1111-111111",Databirth="1-1-1998"},
            new Human { FirstName="Jahseh ", Surname="Dwayne  ", Passport="2222-222222",Databirth="0-0-1990"}
        };
        }
        public void AddHuman()
        {
            Human human = new Human();
            Humans.Insert(0,human);
            SelectedHuman = human;
        }
        public void DeleteHuman()
        {
            if (_selectedhuman != null)
            {
                Humans.Remove(SelectedHuman);
            }
        }
        public void ReportingInCSV()
        {
            using (StreamWriter myOutputStream = new StreamWriter("Myfile.csv"))
            {
                foreach (var item in ReportBox.item)
                {
                    myOutputStream.WriteLine(item.ToString());
                }
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged([CallerMemberName]string prop = "")
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(prop));
        }
    }

View

<Window x:Class="Tutorial_Wpf_MVVM.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:Tutorial_Wpf_MVVM"
        mc:Ignorable="d"
        Title="MVVM_Example" Height="350" Width="525">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <StackPanel Grid.Column="0" DataContext="{Binding SelectedHuman}" Grid.ColumnSpan="2" Margin="0">
            <TextBlock Text="Выбранный элемент" Margin="5,0"  />
            <TextBlock Text="Имя" Margin="5,0" />
            <TextBox Text="{Binding FirstName, UpdateSourceTrigger=PropertyChanged}" Margin="5,0" />
            <TextBlock Text="Фамилие" Margin="5,0" />
            <TextBox Text="{Binding Surname, UpdateSourceTrigger=PropertyChanged}" Margin="5,0" />
            <TextBlock Text="Паспорт(серия-номер)" Margin="5,0" />
            <TextBox Text="{Binding Passport, UpdateSourceTrigger=PropertyChanged}" Margin="5,0" />
            <TextBlock Text="Дата рождения(дд.мм.гггг)" Margin="5,0"/>
            <TextBox Text="{Binding Databirth, UpdateSourceTrigger=PropertyChanged}" Margin="5,0" />

            <Button Click="Add_Click" Margin="5,0">+</Button>
            <Button Click="Delete_Click" Margin="5,0">-</Button>
            <Button Click="ReportingInCSV" Margin="5,0">Экспорт </Button>
        </StackPanel>
        <ListBox Name="ReportBox" Grid.Column="0" Grid.Row="0" ItemsSource="{Binding Humans}"
                 SelectedItem="{Binding SelectedHuman}" Margin="0,235,0,0">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Margin="5">
                        <TextBlock Text="{Binding Path=FirstName}" />
                        <TextBlock Text="{Binding Path=Surname}" />
                        <TextBlock Text="{Binding Path=Passport}" />
                        <TextBlock Text="{Binding Path=Databirth}" />
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>

cs

namespace Tutorial_Wpf_MVVM
{
    /// <summary>
    /// Логика взаимодействия для MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new HumansViewModel();
        }
        private void Add_Click(object sender, RoutedEventArgs e)
        {
            ((HumansViewModel)DataContext).AddHuman();            
        }
        private void Delete_Click(object sender, RoutedEventArgs e)
        {
            ((HumansViewModel)DataContext).DeleteHuman();
        }
        private void ReportingInCSV(object sender, RoutedEventArgs e)
        {
            ((HumansViewModel)DataContext).ReportingInCSV();
        }
    }
}

Собственно в ListBox есть информация. Цель: при нажатии на кнопку генерировать все в csv file

public void ReportingInCSV()
            {
                using (StreamWriter myOutputStream = new StreamWriter("Myfile.csv"))
                {
                    foreach (var item in ReportBox.item)
                    {
                        myOutputStream.WriteLine(item.ToString());
                    }
                }
            }

Но проблема в том что я не могу обратиться к ListBox'у. Как будто нет соответствующего модификатора. Как можно реализовать это??