我有一个ComboBoxin ItemsControl。我使用 WPF 和 MVVM，我无法弄清楚绑定到ComboBox，有人会帮我解决这个问题吗？XAML 和 VM 如下：
<Window x:Class="OutageManagement.Views.MarketAssignmentsView"
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"
mc:Ignorable="d"
Title="Market Selection"
WindowStartupLocation="CenterOwner"
Width="700" Height="850"
DataContext="{Binding MarketAssignmentsVM, Source={StaticResource Locator}}" >
<Grid>
<ItemsControl ItemsSource="{Binding USMarket}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition></ColumnDefinition>
<ColumnDefinition></ColumnDefinition>
</Grid.ColumnDefinitions>
<Label Content="{Binding MarketName}" Height="28"
HorizontalAlignment="Left" Name="lblUSMarketName"
VerticalAlignment="Center" />
<ComboBox Grid.Column="1" Height="23" HorizontalAlignment="Left"
Name="cbUSUsers" VerticalAlignment="Center" MinWidth="140"
ItemsSource="{Binding RelativeSource={RelativeSource
AncestorType=Window}, Path=UserList}"
DisplayMemberPath="UserName"
SelectedValue="{Binding SelectedUserID}"
SelectedValuePath="UserID"/>
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Grid>
</Window>
视图模型：
public class MarketAssignmentsViewModel : ViewModelBase
{
#region Data
ObservableCollection<NOCUserViewModel> _userList;
ObservableCollection<MarketAssignmentViewModel> _usMarket;
ObservableCollection<MarketAssignmentViewModel> _caMarket;
#endregion
#region Constructor
public MarketAssignmentsViewModel()
{
GetUserList();
GetMarketAssignments();
}
#endregion
#region Properties
public ObservableCollection<NOCUserViewModel> UserList
{
get { return _userList; }
}
public ObservableCollection<MarketAssignmentViewModel> USMarket
{
get { return _usMarket; }
}
public ObservableCollection<MarketAssignmentViewModel> CAMarket
{
get { return _caMarket; }
}
#endregion
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}