抛出所选项目的TargetInvocationException已更改

Question

当我更改另一个ItemSource的选择时，我尝试重新生成Devexpress TreeList的内容（TreeList）。但是，运行时会出现以下异常：

  

System.Reflection.TargetInvocationException

代码

    void treeListControl1_SelectedItemChanged(object sender, SelectedItemChangedEventArgs e)
    {
        string st = ww.nList.CurrentCellValue.ToString();
        System.Diagnostics.Debug.WriteLine(st);

        ww.treeList.ItemsSource = null;

        ww.treeList.ItemsSource = drawOrderBook(currCycle, st);
        // drawOrderBook is some complex method that generates the data to displayed based on the filter st and the static data currCycle

    }