[Solved] Problem for BindTo method fo Menu

[Phileas]

I make a practic of Telerik Mvc control.
When I use Menu control, and use bind model function, it prompts me that  "Invalid parameter".
Why?

<%= Html.Telerik().Menu()
        .Name("Menu")
        .BindTo(Model, mappings =>
        {
            mappings.For<tPermission>(binding => binding
                    .ItemDataBound((item, permission) =>
                    {
                        item.Text = permission.PermissionName;
                    })
                    .Children(permission => permission.tPages));
            mappings.For<tPage>(binding => binding
                    .ItemDataBound((item, page) =>
                    {
                        item.Text = page.PageName;
                    }));
        })
%>

Thanks
Phileas