我对xceed CheckComboBox有疑问。

让我说我有这段代码：

<xceed:CheckComboBox Grid.Row="0" Grid.Column="1" Margin="2"
                 ItemsSource="{Binding Path=ListOfCostCenters}"
                 DisplayMemberPath="LoadingCenterCode"
                 SelectedItemsOverride="{Binding Path=SelectedCostCenters,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay}">
<!--<i:Interaction.Triggers>
        <i:EventTrigger EventName="ItemSelectionChanged">
            <i:InvokeCommandaction Command="{Binding Path=CompareSelectionCmd}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>-->                    
</xceed:CheckComboBox>

组合框已正常填充。但是没有检查我从XML加载的选定项目。为什么？

我这样加载XML：

List<LoadingCenter> selectedLoadingCentersXml = _moduleConfig.getconfig<UserConfig>().LoadingCenters;

//We need to get the same Object which is in ItemSource (CostCenters) of checkBox component.
foreach (LoadingCenter center1 in selectedLoadingCentersXml)
{
    selectedLoadingCenters.Add(center1);
}

if (selectedLoadingCenters.Count > 0)
{
    //Fill the property with list of objects from CostCenters which are the same with objects from loaded XML file.
    SelectedCostCenters = new ObservableCollection<LoadingCenter>(selectedLoadingCenters);                        
}
else if (selectedLoadingCenters.Count == 0)
{
    SelectedCostCenters = new ObservableCollection<LoadingCenter>();
}    

我将XML文件存储在我从中读取的数据库中。