Kendo Grid-Treeview拖放问题

Question

我使用kendo树视图作为网格行的放置目标。 当在树视图中删除行时，此代码给出以下错误：未捕获的TypeError：item.level不是函数。

我该如何解决这个问题？

        <%=Html.Kendo().TreeView()
            .Name("treeview")
            .Checkboxes(checkboxes => checkboxes
                .Name("checkedActivities")
                .CheckChildren(true)
            )
            .LoadOnDemand(true)
            .DataTextField("descriptionText")
            .DataSource(dataSource => dataSource
                .Read(read => read.Action("Activity", "Activity"))
                )    
            .DragAndDrop(true)
        %>

        <%: Html.Kendo().Grid<Web.Models.Model>() 
        .Name("grid")
        .BindTo((IEnumerable<Web.Models.Model>)ViewBag.List)
        .Columns(columns =>
        {
            columns.Bound(p => p.PK).Title("PK").Hidden(true);
            columns.Bound(p => p.CODE).Title("Code");
            columns.Bound(p => p.DESCRIPTION).Title("Description");                     
        })       

        .DataSource(dataSource => dataSource
            .Ajax()
            .Model(Model => Model.Id(p => p.PK))
        )            
        %>


<script>    
    $("#grid").kendoDraggable({
        filter: "tr",  
        hint: function (element) { 
            return element.clone().css({
                "opacity": 0.6,
                "background-color": "#0cf"
            });
        }
    });

$("#treeview").kendoDropTarget({
    drop: function (e) { 
        console.log("drop");

        var dataSourceGrid = $("#grid").data("kendoGrid").dataSource;
        var dataSourcetreeview = $("#treeview").data("kendoTreeView").dataSource;

        var draggableElement = e.draggable.currentTarget,                
            dataItem = dataSourceGrid.getByUid(draggableElement.data("uid")); 

        if (dataItem == undefined) {
            dataItem = dataSourcetreeview.getByUid(draggableElement.data("uid")); 
        }

        else {
            dataSourcetreeview.add({ descriptionText: dataItem["DESCRIPTION"] });                                
        }
    }
});
</script>