private void load_data_to_tree()
{
US_V_DM_DON_VI_2 v_us = new US_V_DM_DON_VI_2();
DS_V_DM_DON_VI_2 v_ds = new DS_V_DM_DON_VI_2();
v_us.FillDataset(v_ds);
m_tree_don_vi.ParentFieldName = DM_DON_VI.ID_DON_VI_CAP_TREN;
m_tree_don_vi.DataSource = v_ds.Tables[0];
m_tree_don_vi.ExpandAll();
}