Hi Tanya,
thank you about your answer. I did make what you said, but i still can see only the root element. This is my code, now a concrete example:

the C# code about helper class:

    public class navigatorTree
    {
        public ACIDServices.NavigatorRole element { get; set; }
        public List<navigatorTree> children;

    }

        public static List<navigatorTree> getNavigatorTree(List<ACIDServices.NavigatorRole> tree)
        {
            List<navigatorTree> result = new List<navigatorTree>();
            navigatorTree tempElement = new navigatorTree();
            List<ACIDServices.NavigatorRole> tempResult = tree.FindAll(delegate(ACIDServices.NavigatorRole p) { return p.HID == 0; });
            foreach (ACIDServices.NavigatorRole navRole in tempResult)
            {
                tempElement = new navigatorTree();
                tempElement.element = navRole;
                tempElement.children = getSubNavigatorTree(navRole, tree);
                result.Add(tempElement);
            }

            return result;
        }

The code, which i use to databind the xamDataTree:

                List<ACIDServices.NavigatorRole> navigatorRole = new List<ACIDServices.NavigatorRole>();
                asc.GetNavigator(out navigatorRole, SESSION.Session.Get("SessionID").ToString(), (int)SESSION.Session.Get("ofpRoleID"), true);
                Resources.Add("navigatorTree", ACID_WPF_FE.AppGlobalCode.treeHelper.getNavigatorTree(navigatorRole));

// Now i have a hierarchical List from navigatorTree. The property "children" has more items from navigatorTree, which has another children with list of navigatorTree...

and the XAML:

        <ig:XamDataTree HorizontalAlignment="Left" Name="xamDataTree1" VerticalAlignment="Top"
                        ItemsSource="{DynamicResource navigatorTree}"
                        Width="125">
            <ig:XamDataTree.GlobalNodeLayouts>
                <ig:NodeLayout Key="element" TargetTypeName="ACID_WPF_FE.AppGlobalCode.navigatorTree" DisplayMemberPath="element.NAME" />
            </ig:XamDataTree.GlobalNodeLayouts>
        </ig:XamDataTree>

and after F5, i can see only the first level from datasource (List<navigatorTree>) :(

In the Example browser, i saw that the itemsSource is in XML. Is it the key from the house?