关于wpf中datatemplate和binding的一些问题

[不愿透露姓名的万驰先生]

/// <summary>
/// DatatemplateDemo.xaml 的交互逻辑
/// </summary>
public partial class DatatemplateDemo : Window
{
private readonly MainViewModel _viewModel = new MainViewModel();
public DatatemplateDemo()
{
InitializeComponent();
string[] files = new string[2] { @"C:\Users\lenovo-wanchi\Desktop\rvt17.ifc", @"C:\Users\lenovo-wanchi\Desktop\site.ifc" };
IfcStore store = MainWindow. FederationFromDialogbox(files);
_viewModel.ModelStore = store;
this.DataContext = _viewModel;
usercontrol.DataContext = _viewModel;
}
}




<Window x:Class="WPF.DatatemplateDemo"
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:WPF"
mc:Ignorable="d"
xmlns:xbim="http://schemas.Xbim.com/Presentation"
Title="DatatemplateDemo" Height="500" Width="1000">
<Window.Resources>
<DataTemplate x:Key="datatemplate">
<Grid>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition Height="30"/>
</Grid.RowDefinitions>
<Button Content="{Binding Path=Title}" x:Name="button" Grid.Row="1" VerticalAlignment="Center" Height="20" Width="100"/>
<xbim:DrawingControl3D Model ="{Binding Path=ModelStore}" Grid.Row="0" Focusable="True" Width="Auto" Height="Auto" >
<xbim:DrawingControl3D.Background>
<LinearGradientBrush EndPoint="0.5,1" MappingMode="RelativeToBoundingBox" StartPoint="0.5,0">
<GradientStop Color="#FFB9B1B1" Offset="1"/>
<GradientStop Color="#FFFAF8FF"/>
</LinearGradientBrush>
</xbim:DrawingControl3D.Background>
</xbim:DrawingControl3D>
</Grid>
</DataTemplate>
</Window.Resources>

<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition Width="30"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<UserControl ContentTemplate="{StaticResource datatemplate}" x:Name="usercontrol" Grid.Column="0"></UserControl>
<xbim:DrawingControl3D Model ="{Binding Path=ModelStore}" Grid.Column="2" Focusable="True" Width="Auto" Height="Auto" Margin="0,0,0,30" >
<xbim:DrawingControl3D.Background>
<LinearGradientBrush EndPoint="0.5,1" MappingMode="RelativeToBoundingBox" StartPoint="0.5,0">
<GradientStop Color="#FFB9B1B1" Offset="1"/>
<GradientStop Color="#FFFAF8FF"/>
</LinearGradientBrush>
</xbim:DrawingControl3D.Background>
</xbim:DrawingControl3D>
</Grid>
</Window>



请问我前台资源中的binding错在什么地方，数据传不进去，写在window中的控件，就能binding成功。
请大佬们解答小白的疑惑

[不愿透露姓名的万驰先生]

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