Ok Tried this ;

Code:
 Select Case Me.CmbTruckTyp.SelectedItem.ToString

    Case "Mercedes-Benz"
         cmdMercBenzModels.Visible = True
         cmbDafModels.Visible = False
    Case "Daf"
         cmdMercBenzModels.Visible = False
         cmbDafModels.Visible = True
    Case Else
         cmdMercBenzModels.Visible = False
         cmbDafModels.Visible = False

  End Select
At run time, I have the error -

NullReferenceException was unhandled by user code
Object Reference not set to an instance of an object

This line is higlighted in yellow;

Code:
Select Case Me.CmbTruckTyp.SelectedItem.ToString
ANy assistance please