DragDrop in DataGrid

[abbe]

Can someone tell me how to Drop something in DataGrid.

private void Interaction_dgr_DragDrop(object sender, System.Windows.Forms.DragEventArgs e)
{
DataGrid.HitTestInfo hti = Interaction_dgr.HitTest(new Point(e.X, e.Y));

MessageBox.Show(hti.Column.ToString());
}
My HitTestInfo object return -1 when i'm trying to get Row and Column properties.