title: combobox return System.Data.DataRowView when dataset return value is null
body: <p>Try to bind combobox but returning System.Data.DataRowView when ds.Tables[0].Rows.Count >0 but the return value is null.</p>
  
  <pre><code>cbox.DataSource = ds.Tables[0];
  cbox.DisplayMember = displayValue;
  cbox.SelectedIndex = -1;
  </code></pre>