ActiveDockable issues

[nasterhe]

public override IRootDock CreateLayout()
{
    ProjectTreeViewModel = new ProjectTreeViewModel()
    {
        Id = "ProjectTreeView",
        Title = "ProjectTree",
        CanClose = false,
        CanFloat = false,
        CanPin = false,
      };
    var prj = new ProportionalDock
    {
        Proportion = 0.15,
        VisibleDockables = CreateList<IDockable>
   (
       new ToolDock
       {
           VisibleDockables = CreateList<IDockable>
           (
               ProjectTreeViewModel
           ),
       }
   )
    };
    TableHelperViewModel = new TableHelperViewModel()
    {
        Id = "TableHelperView",
        CanClose = false,
        CanFloat = false,
        CanPin = false,
      };
    var table = new ProportionalDock
    {
        Proportion = 0.7,
        VisibleDockables = CreateList<IDockable>
   (
       new ToolDock
       {
           VisibleDockables = CreateList<IDockable>
           (
               TableHelperViewModel
           ),
           GripMode = GripMode.Hidden
       }

   )
    };
    PropertyControlViewModel = new PropertyControlViewModel()
    {
        Id = "PropertyControlView",
        Title = "Property",
        CanClose = false,
        CanFloat = false,
        CanPin = false,
    };
    var prop = new ProportionalDock
    {
        Proportion = 0.15,
        VisibleDockables = CreateList<IDockable>
   (
       new ToolDock
       {
           VisibleDockables = CreateList<IDockable>
           (
               PropertyControlViewModel
           ),
       }

   )
    };
    var windowLayout = CreateRootDock();
    var windowLayoutContent = new ProportionalDock
    {
        Orientation = Orientation.Horizontal,
        IsCollapsable = false,
        ActiveDockable = prj,
        VisibleDockables = CreateList<IDockable>
        (
            prj,
            new ProportionalDockSplitter(),
            table,
            new ProportionalDockSplitter(),
            prop
        )
    };
    windowLayout.IsCollapsable = false;
    windowLayout.VisibleDockables = CreateList<IDockable>(windowLayoutContent);
    windowLayout.ActiveDockable = windowLayoutContent;

    var rootDock = CreateRootDock();

    rootDock.IsCollapsable = false;
    rootDock.VisibleDockables = CreateList<IDockable>(windowLayout);
    rootDock.ActiveDockable = windowLayout;
    rootDock.DefaultDockable = windowLayout;
    
    _rootDock = rootDock;

    return rootDock;
}

I would expect the default ActiveDockable to be ProjectTreeViewModel, but the actual effect is PropertyControlViewModel.Please tell me where is my code wrong, thanks.