I am trying to implement the drag and drop functionality within a xamDataGrid. I have all the event handlers hooked up. In the drop event handler i have following code:

void xamDataGrid2_Drop(object sender, DragEventArgs e)
        {
            XamDataGrid dragSource2 = xamDataGrid;
            XamDataGrid dragTarget = sender as XamDataGrid;

            //Get Instance of the dragger DataRecordPresenter and DataRecord
            DataRecordPresenter draggedPresenter = e.Data.GetData(typeof(DataRecordPresenter)) as DataRecordPresenter;
            DataRecord draggedRecord = draggedPresenter.Record as DataRecord;

            // If there are not items in the Drag Target, just add the dragged record
            if (dragTarget.Records.Count == 0)
            {
                dragTarget.DataItems.Add(draggedRecord.DataItem);
                dragSource2.ActiveRecord = null;
                return;
            }
            // There are items already in the Drag Target, so we need to determine where to insert the dragged record
            // depending on the Mouse position.
            else
            {
                DataRecord existingRecord = dragTarget.Records[0] as DataRecord;
                // Records have to be of the same type to be in the same FieldLayout
                if (existingRecord.DataItem.GetType() == draggedRecord.DataItem.GetType())
                {
                    // Insert Logic based on the Mouse position over the Drag Target
                    DataRecordPresenter tempPresenter = DataRecordPresenter.FromRecord(dragTarget.Records[0]) as DataRecordPresenter;
                    Point positionOfDrop = e.GetPosition(dragTarget);
                    int i = GetRecordInsertPosition(positionOfDrop, tempPresenter);
                    dragTarget.DataItems.Insert(i, draggedRecord.DataItem);

                    // force the ActiveRecord to null so that an erroneous drag in the Adorner will not be performed
                    dragSource2.ActiveRecord = null;
                }
            }
        }

but i got exception here: dragTarget.DataItems.Insert(i, draggedRecord.DataItem);

The dragTarget.DataItems is 0, but I do have dragTarget.Records.Count =4 (i have 4 records in the grid). If I use 2 xamDatagrid and drag from grid 1 to grid 2, dragTarget.DataItems would show the correct number of data items. It's not working from within one xamDatagrid ... why is this?