Print a report code works but not on preview

[bunji]

I have my reports with the following code but on preview the code doesnt seem to run untill the it is actually printed.

Code is:

Private Sub Detail_Format(Cancel As Integer, FormatCount As Integer)
    Me.ReleaseDescrip = DLookup("[Release_Description]", "tblReleases", "[Release_type] = Reports![rptAirFrame]![AF_Release] AND [Base] = Reports![rptAirFrame]![Base]")
End Sub

Private Sub PageHeaderSection_Format(Cancel As Integer, FormatCount As Integer)

    If Base.Properties!Text = "LTN" Then
        Address.Caption = "  Address 2"
    Else
        Address.Caption = "   Address 1"
    End If
    
    If Me.Based_Customer = True Then
    
    Me.WO_Number_IfBased.Visible = True
    Me.Wo_Number_IFbased_Label.Visible = True
    Me.CustomerWA.Visible = False
    Me.CustomerWA_Label.Visible = False
    Me.WO_Number.Visible = False
    Me.NotBasedTxt.Visible = False
    Me.IsBasedtxt.Visible = True
    Me.Customer_Scheduled_WO.Visible = True
    
    End If

End Sub