Combo box loading error

Hi,
 
I have a scenario:I loaded my combox box with the datatable in my Form Load as below:
 

m_dtDelayedDeliveryDays = GetDelayedDeliveryDays()
 

 
       For Each dr As DataRow In m_dtDelayedDeliveryDays.Rows
           Me.cmbDelayedDeliveryDays.Items.Add(dr("DeliveryDelayDays"))
       Next
 
       cmbDelayedDeliveryDays.DataSource = m_dtDelayedDeliveryDays
       cmbDelayedDeliveryDays.DisplayMember = "DeliveryDelayDays"
       cmbDelayedDeliveryDays.ValueMember = "DeliveryDelayDaysID"

 
In also i am able to pick the Id based on the user selection as below:

Private Sub cmbDelayedDeliveryDays_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cmbDelayedDeliveryDays.SelectedIndexChanged
 
        cmbDelayedDeliveryDays.Refresh()
        Dim selectedDataRow As DataRow = DirectCast(cmbDelayedDeliveryDays.SelectedItem, DataRowView).Row
        Dim delayId As Integer = Convert.ToInt32(selectedDataRow("DeliveryDelayDaysID"))
 

    End Sub

My combo box is loaded with values like 0,3,7,15,20,30..
With the above code my combo box is with default value 0. I want me combo box to be empty by default.
 
Please help.
 
Thanks.