Data changes not persisting back to Entity Framework on an MVVM application

I'll post my code first, then ask my question.

XAML:

<Window
         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:FootballPool" mc:Ignorable="d" x:Class="MainWindow"
         xmlns:system="clr-namespace:System;assembly=mscorlib"
         Title="MainWindow" Height="350" Width="525" Margin="5"><Window.Resources><local:MainWindowVM x:Key="ViewModel" /><ObjectDataProvider x:Key="YearList"
                                 ObjectType="{x:Type local:MainWindowVM}"
                                 MethodName="YearList" /><ObjectDataProvider x:Key="WeekList"
                                 ObjectType="{x:Type local:MainWindowVM}"
                                 MethodName="WeekList"><ObjectDataProvider.MethodParameters><system:Int32>0</system:Int32></ObjectDataProvider.MethodParameters></ObjectDataProvider></Window.Resources><Grid><TabControl Margin="0,0,0,37"><TabItem Header="Standings"><Grid Background="#FFE5E5E5"/></TabItem><TabItem Header="Users"><Grid Background="#FFE5E5E5"><DataGrid
                             x:Name="dgUsers"
                             DataContext="{Binding Source={StaticResource ViewModel}}"
                             ItemsSource="{Binding Users, Mode=TwoWay}" AutoGenerateColumns="False"
                             IsSynchronizedWithCurrentItem="True"><DataGrid.Columns><DataGridTextColumn Binding="{Binding FirstName}" ClipboardContentBinding="{x:Null}" Header="First Name"/><DataGridTextColumn Binding="{Binding LastName}" ClipboardContentBinding="{x:Null}" Header="Last Name"/><DataGridTextColumn Binding="{Binding Email}" ClipboardContentBinding="{x:Null}" Header="Email"/><DataGridTextColumn Binding="{Binding Password}" ClipboardContentBinding="{x:Null}" Header="Password"/></DataGrid.Columns></DataGrid></Grid></TabItem><TabItem Header="Weekly Settings"><Grid Background="#FFE5E5E5"><Grid x:Name="Grid1" HorizontalAlignment="Left" VerticalAlignment="Top" Background="#FFC8C8C8" Margin="238,27,0,0" DataContext="{Binding SelectedItem, ElementName=listBox}"><Grid.ColumnDefinitions><ColumnDefinition Width="Auto"/><ColumnDefinition Width="Auto"/></Grid.ColumnDefinitions><Grid.RowDefinitions><RowDefinition Height="Auto"/><RowDefinition Height="Auto"/><RowDefinition Height="Auto"/><RowDefinition Height="Auto"/><RowDefinition Height="Auto"/></Grid.RowDefinitions><Label Content="Year:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="0" VerticalAlignment="Center"/><TextBox x:Name="Year" Grid.Column="1" HorizontalAlignment="Left" Height="24" Margin="3" Grid.Row="0" Text="{Binding Year, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/><Label Content="Week Number:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="1" VerticalAlignment="Center"/><TextBox x:Name="WeekNumberTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="1" Grid.Row="1" Text="{Binding WeekNumber, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/><Label Content="Begin Date:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="2" VerticalAlignment="Center"/><DatePicker x:Name="BeginDateDatePicker" Grid.Column="1" HorizontalAlignment="Left" Margin="3" Grid.Row="2" SelectedDate="{Binding BeginDate, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center"/><Label Content="End Date:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="3" VerticalAlignment="Center"/><DatePicker x:Name="EndDateDatePicker" Grid.Column="1" HorizontalAlignment="Left" Margin="3" Grid.Row="3" SelectedDate="{Binding EndDate, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center"/><Label Content="Cost:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="4" VerticalAlignment="Center"/><TextBox x:Name="CostTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="4" Text="{Binding Cost, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/></Grid><Button x:Name="btnNewWeek" Content="New Week" HorizontalAlignment="Left" Height="23" Margin="384,192,0,0" VerticalAlignment="Top" Width="75"/><ComboBox x:Name="cboYear"
                                   HorizontalAlignment="Left" Margin="94,14,0,0" 
                                   VerticalAlignment="Top" Width="56"  
                                   IsSynchronizedWithCurrentItem="True" 
                                   ItemsSource="{Binding Mode=OneWay, Source={StaticResource YearList}}"><ComboBox.SelectedItem><Binding Source="{StaticResource WeekList}"
                                          Path="MethodParameters[0]"
                                          BindsDirectlyToSource="True"
                                          UpdateSourceTrigger="PropertyChanged" /></ComboBox.SelectedItem></ComboBox><ListBox x:Name="listBox" HorizontalAlignment="Left" Height="136" Margin="95,51,0,0" VerticalAlignment="Top" Width="55" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Source={StaticResource WeekList}}" DisplayMemberPath="WeekNumber" /><Label Content="Year:" HorizontalAlignment="Left" Margin="27,10,0,0" VerticalAlignment="Top"/><Label Content="Week:" HorizontalAlignment="Left" Margin="27,51,0,0" VerticalAlignment="Top"/></Grid></TabItem></TabControl><Button Content="Save" HorizontalAlignment="Right" Height="27" Margin="0,0,5,5" VerticalAlignment="Bottom" Width="80" Click="Button_Click"/></Grid></Window>

ViewModel:

Imports System.Collections.ObjectModel
Imports System.ComponentModel
Imports System.Collections.Specialized
Public Class MainWindowVM
         Implements INotifyPropertyChanged
         Implements INotifyCollectionChanged
         Dim dbcontext As New FootballPoolEntities
         Private _Users As ObservableCollection(Of User)
         Private _Settings As ObservableCollection(Of ScheduleSetting)
         Public Property Users As ObservableCollection(Of User)
             Get
                 Return _Users
             End Get
             Set(value As ObservableCollection(Of User))
                 _Users = value
                 RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("Users"))
             End Set
         End Property
         Public Property Settings As ObservableCollection(Of ScheduleSetting)
             Get
                 Return _Settings
             End Get
             Set(value As ObservableCollection(Of ScheduleSetting))
                 _Settings = value
                 RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("Settings"))
             End Set
         End Property
         Public Sub New()
             _Users = New ObservableCollection(Of User)(dbcontext.Users.ToList)
             _Settings = New ObservableCollection(Of ScheduleSetting)(dbcontext.ScheduleSettings.ToList)
             AddHandler Users.CollectionChanged, AddressOf OnUsersCollectionChanged
             AddHandler Settings.CollectionChanged, AddressOf OnSettingsCollectionChanged
         End Sub
         Public Event PropertyChanged(sender As Object, e As PropertyChangedEventArgs) Implements INotifyPropertyChanged.PropertyChanged
         Public Event CollectionChanged(sender As Object, e As NotifyCollectionChangedEventArgs) Implements INotifyCollectionChanged.CollectionChanged
         Private Sub OnUsersCollectionChanged(sender As Object, e As NotifyCollectionChangedEventArgs)
             If e.Action = NotifyCollectionChangedAction.Add Then
                 For Each item In e.NewItems
                     dbcontext.Users.Add(item)
                 Next
             End If
             If e.Action = NotifyCollectionChangedAction.Remove Then
                 For Each item In e.OldItems
                     dbcontext.Users.Remove(item)
                 Next
             End If
         End Sub
         Private Sub OnSettingsCollectionChanged(sender As Object, e As NotifyCollectionChangedEventArgs)
             If e.Action = NotifyCollectionChangedAction.Add Then
                 For Each item In e.NewItems
                     dbcontext.ScheduleSettings.Add(item)
                 Next
             End If
             If e.Action = NotifyCollectionChangedAction.Remove Then
                 For Each item In e.OldItems
                     dbcontext.ScheduleSettings.Remove(item)
                 Next
             End If
         End Sub
         Public Sub SaveChanges()
             dbcontext.SaveChanges()
         End Sub
         Public Sub NewWeek()
             Dim newWeek As New ScheduleSetting
             Settings.Add(newWeek)
         End Sub
         Public Function WeekList(SelectedYear As Int32) As ObservableCollection(Of ScheduleSetting)
             If SelectedYear = 0 Then
                 Return Nothing
                 Exit Function
             End If
             Return New ObservableCollection(Of ScheduleSetting)(Settings.Where(Function(c) c.Year = SelectedYear).ToList)
         End Function
         Public Function YearList() As List(Of Int32)
             Return dbcontext.ScheduleSettings _
                 .Select(Function(x) x.Year) _
                 .Distinct.ToList()
         End Function
End Class

The problem I am having is that my listbox fills with Settings objects via the "WeekList" method and an ObjectDataProvider.  My details grid has it's datacontext bound to the SelectedItem of that listbox.  When I make changes to the data, they are not persisting back to the Entity Framework when I perform the savechanges.  Am I missing something in the binding, should I be handling the Master-Detail differently?  Or is there something in my ViewModel which I need to add?

I appreciate any help someone can offer.  Thanks.

Ruler of the undershorts