How do I get two subclassed TreeViews to share a panel with a splitter?

I have 2 derived TreeView controls:

  internal class TreeConfiguration : TreeView

  internal class TreeProject : TreeView

How do I get them docked in a panel?

In the constructor of my Form I have this:

public FormSettings()
{
  InitializeComponent();

  TreeNode[] allNodes = ProjectHelper.getAllNodes();
  TreeConfiguration tc = new TreeConfiguration(allNodes);
  TreeProject tp = new TreeProject(allNodes);
  panelTree.Controls.Add(this.TreeConfiguration);
  panelTree.Controls.Add(splitterTree);
  panelTree.Controls.Add(this.TreeProject);
}

Compile Error:
...'FormSettings' does not contain a definition for 'TreeConfiguration' ...

Do I need to mess with the Designer code to add these TreeViews to my form?

Thanks in advance.