Dragging and dropping a row in RadGridView does not work.

public class DragAndDropRadGrid : RadGridView
{
        
    public DragAndDropRadGrid() 
    {  
        this.MultiSelect = true;                       
        
        //handle drag and drop events for the grid through the DragDrop service
        RadDragDropService svc = 
                this.GridViewElement.GetService<RadDragDropService>();
        svc.PreviewDragStart += svc_PreviewDragStart;
        svc.PreviewDragDrop += svc_PreviewDragDrop;
        svc.PreviewDragOver += svc_PreviewDragOver;

        //register the custom row selection behavior
        var gridBehavior = this.GridBehavior as BaseGridBehavior;
        gridBehavior.UnregisterBehavior(typeof(GridViewDataRowInfo));
        gridBehavior.RegisterBehavior(typeof(GridViewDataRowInfo),
                                    new RowSelectionGridBehavior());

    }

    //required to initiate drag and drop when grid is in bound mode
    private void svc_PreviewDragStart(object sender, PreviewDragStartEventArgs e)
    {
        e.CanStart = true;
    }

    //gather drag/source grid and target/destination information and initiate 
    //the move of selected rows
    private void svc_PreviewDragDrop(object sender, RadDropEventArgs e)
    {
        var rowElement = e.DragInstance as GridDataRowElement;

        if (rowElement == null)
        {
            return;
        }
        e.Handled = true;

        var dropTarget = e.HitTarget as RadItem;
        var targetGrid = dropTarget.ElementTree.Control as RadGridView;
        if (targetGrid == null)
        {
            return;
        }

        var dragGrid = rowElement.ElementTree.Control as RadGridView;
        if (targetGrid != dragGrid)
        {
            e.Handled = true;
            //append dragged rows to the end of the target grid
            int index = targetGrid.RowCount;

            //Grab every selected row from the source grid, including the current row
            List<GridViewRowInfo> rows = 
                                dragGrid.SelectedRows.ToList<GridViewRowInfo>();
            if (dragGrid.CurrentRow != null)
            {
                GridViewRowInfo row = dragGrid.CurrentRow;
                if (!rows.Contains(row))
                    rows.Add(row);
            }
            this.MoveRows(targetGrid, dragGrid, rows, index);
        }
    }

    private void svc_PreviewDragOver(object sender, RadDragOverEventArgs e)
    {
        if (e.DragInstance is GridDataRowElement)
        {
            e.CanDrop = e.HitTarget is GridDataRowElement || 
                        e.HitTarget is GridTableElement ||
                        e.HitTarget is GridSummaryRowElement;
        }
    }
       
    private void MoveRows(RadGridView targetGrid, RadGridView dragGrid, 
                            IList<GridViewRowInfo> dragRows, int index) 
    { 
        dragGrid.BeginUpdate();
        targetGrid.BeginUpdate();
        for (int i = dragRows.Count - 1; i >= 0; i--)
        {
            GridViewRowInfo row = dragRows[i];
            if (row is GridViewSummaryRowInfo)
            {
                continue;
            }
            if (targetGrid.DataSource == null)
            {
                //unbound scenario
                GridViewRowInfo newRow = targetGrid.Rows.NewRow();

                foreach (GridViewCellInfo cell in row.Cells)
                {
                    if (newRow.Cells[cell.ColumnInfo.Name] != null)
                        newRow.Cells[cell.ColumnInfo.Name].Value = cell.Value;
                }

                targetGrid.Rows.Insert(index, newRow);

                row.IsSelected = false;
                dragGrid.Rows.Remove(row);
            }
            else if (typeof(DataSet).IsAssignableFrom(targetGrid.DataSource.GetType()))
            {
                //bound to a dataset scenario
                var sourceTable = ((DataSet)dragGrid.DataSource).Tables[0];
                var targetTable = ((DataSet)targetGrid.DataSource).Tables[0];

                var newRow = targetTable.NewRow();
                foreach (GridViewCellInfo cell in row.Cells)
                {
                    newRow[cell.ColumnInfo.Name] = cell.Value;
                }

                sourceTable.Rows.Remove(((DataRowView)row.DataBoundItem).Row);
                targetTable.Rows.InsertAt(newRow, index);
            }
            else if (typeof(IList).IsAssignableFrom(targetGrid.DataSource.GetType()))
            {
                //bound to a list of objects scenario
                var targetCollection = (IList)targetGrid.DataSource;
                var sourceCollection = (IList)dragGrid.DataSource;
                sourceCollection.Remove(row.DataBoundItem);
                targetCollection.Add(row.DataBoundItem);
            }
            else
            {
                throw new ApplicationException("Unhandled Scenario");
            }
            index++;
        }
        dragGrid.EndUpdate(true);
        targetGrid.EndUpdate(true);
    }

   
}

//initiates drag and drop service for clicked rows
public class RowSelectionGridBehavior : GridDataRowBehavior
{
    protected override bool OnMouseDownLeft(MouseEventArgs e)
    {
        GridDataRowElement row = this.GetRowAtPoint(e.Location) as GridDataRowElement;
        if (row != null)
        {
            RadGridViewDragDropService svc =
                        this.GridViewElement.GetService<RadGridViewDragDropService>();
            svc.Start(row);
        }
        return base.OnMouseDownLeft(e);
    }
}