DatagridComboBoxColumn排序

XAML编号:

<DataGridComboBoxColumn Header="Department" 
    ItemsSource="{Binding Source={StaticResource departmentViewSource}}" 
    DisplayMemberPath="Title" SelectedValuePath="ID" SortDirection="Ascending"
    SelectedValueBinding="{Binding DepartmentID, Mode=TwoWay, ValidatesOnDataErrors=True, UpdateSourceTrigger=PropertyChanged}"
    SortMemberPath="lkpDepartments.Sequence" />

谢谢。