无法使用实体框架将复杂属性绑定到Gridview

Question

I have the following code which should bind some data to a gridview but its not working.

THe district manager object has a Brand. As you can see in the screenshot the brand is correctly filled in with data.

 private void LoadData()
        {
            List<DealerDistrictManager> listDealerDistrictManager = DistrictManagerBL.GetAllDealersWithDistrictManagers();
            DistrictManagersGrid.DataSource = listDealerDistrictManager;
            DistrictManagersGrid.DataBind();


     <asp:BoundColumn DataField="DistrictManagerId" Visible="False"></asp:BoundColumn> 
        <asp:BoundColumn DataField="Brand.Name" meta:resourcekey="BrandHeader"></asp:BoundColumn>


 public class DealerDistrictManager
    {
        public int DistrictManagerId { get; set; }
        public string Nuteres { get; set; } 
        public string DealerNumber { get; set; }
        public virtual Brand Brand { get; set; }
        public int DistrictNumber { get; set; }
        public string Name { get; set; }
    }

 public class Brand
    {
        public int BrandId { get; set; }
        public string Name { get; set; }
    }

Update1

public List<DealerDistrictManager> GetAllDealersWithDistrictManagers()
    {

            return  (from d in _context.Dealers
                      from m in _context.DistrictManagers
                      where d.Nuteres == m.DealerNuteres
                     select new DealerDistrictManager
                                { 
                                    DistrictManagerId= m.DistrictManagerId,
                                    Nuteres = d.Nuteres,
                                    DealerNumber = d.DealerNumber,
                                    Brand  = m.Brand,
                                    DistrictNumber = m.DistrictNumber,
                                    Name = m.Name

                                 }).ToList<DealerDistrictManager>(); 

    }

Answer 1

This post also speaks about the same / similar problem. Where it "randomly" occurs. The solution that the questioner found was to use:

<%#Eval("contentsection.Id") %>

The post mentioned has a lot of answers (including an accepted one) that will clarify a lot I presume.