Set ViewProjection (Bug ?)

I’m working on my first RhinoScript, but, there is a problem.
Rhinoscript Helpfile tells me :
Returns or sets a view’s projection mode. A view’s projection mode can be either parallel or perspective.

Option Explicit

Call NViewports()

Sub NViewports()

Dim strNewTitle, strOldTitle, blnResult ,blnProjection
Call Rhino.RenameView("Top", "TopEx")
Rhino.Command "_NewViewport"
strNewTitle = Rhino.StringBox("Set name of new viewport","","New Viewport")
If Not IsNull(strNewTitle) Then
    strOldTitle = Rhino.CurrentView("Top")
    Call Rhino.RenameView(strOldTitle, strNewTitle)
    blnResult = Rhino.IsViewPerspective(strNewTitle)
    If blnResult = False Then
        blnProjection =    Rhino.ViewProjection (strNewTitle, 2) '!!! Nothing changed !!!
    End If
End If

End Sub

I use integer 2, but nothing will change to perspective mode…
This problem relates to Rhino V4

Best regards

AAHHOo , NewVieport must be deactivated and activated (also a refresh)