After
cmbDelayedDeliveryDays.ValueMember = "DeliveryDelayDaysID"
put the following
cmbDelayedDeliveryDays..SelectedIndex = -1
In
Sub cmbDelayedDeliveryDays_SelectedIndexChanged
you need to wrap any code that refers to
cmbDelayedDeliveryDays.SelectedItem
with a check on
.SelectedIndex
e.g.
If cmbDelayedDeliveryDays.SelectedIndex > 0 Then
Debug.Print(cmbDelayedDeliveryDays.SelectedValue.ToString())
End If