private void cbULUnit_SelectedValueChanged( object sender, EventArgs e )
{
if (edtULValue.Quantity == null)
edtULValue.Quantity = new Quantity();
if (edtULValue.Quantity.Unit == null)
edtULValue.Quantity.Unit = new StandardUnit();
edtULValue.Quantity.Unit.Unit = cbULUnit.SelectedValue as string;
if (_errorLimit != null)
edtErrorLimit.Text = _errorLimit.ToString();
}