title: Bound columns require a field or property access expression in ASP.NET MVC
body: <p>I have relations one to many in DB ( i used entity interface to generate associations between 2 obj)
  Im getting error:
  Bound columns require a field or property access expression</p>
  
  <p>My code:</p>
  
  <p>in view:</p>
  
  <pre><code>  Html.Telerik()
          .Grid&lt;Y.Orders.Models.Orders&gt;("orders")
  
          .Name("Orders")
          .DataKeys(dataKeys =&gt; dataKeys.Add(o =&gt; o.Id))
          //.Pageable(paging =&gt; paging.PageSize(20).Style(GridPagerStyles.PageSizeDropDown | GridPagerStyles.NextPreviousAndNumeric))
          .Columns(columns =&gt;
          {
              columns.Command(commands =&gt;
              {
                  commands.Custom("comments").ButtonType(GridButtonType.Text).Text("Szczegóły").Action("Index", "Komentarze");
              });
              columns.Bound(o =&gt; o.Tytul).Title("Title");
              columns.Bound(o =&gt; o.Deliveries.Sum(m=&gt;m.deliveryTime)).Title("Time of order");
          })
          .Filterable()
          .Sortable(sort =&gt;
          {
              sort.SortMode(GridSortMode.MultipleColumn); sort.OrderBy(ord =&gt;
              {
                  ord.Add(o =&gt; o.Time).Descending();
  
              });
          })
          .Groupable(grouping =&gt; grouping.Groups(groups =&gt;
          {
              groups.Add(c =&gt; c.Users.Firms.Name);
          }))
          .Render();
  </code></pre>
  
  <p>in entity model:</p>
  
  <pre><code>    public ObjectSet&lt;Deliveries&gt;  Deliveries
      {
          get
          {
              if ((_ Deliveries
   == null))
                  {
                      _Deliveries = base.CreateObjectSet&lt;Deliveries&gt;("Deliveries");
                  }
                  return _Deliveries;
              }
          }
          private ObjectSet&lt;Deliveries&gt; _Deliveries;
  </code></pre>
  
  <p>In deliveries i havnt any null.</p>
  
  <p>Where is problem ?</p>