I think a lot of developers are facing the problem of try to display page numbers by using SSRS 2008 R2.
There is an alternative solution <
Here is working expression:
=Microsoft.VisualBasic.Interaction.Switch(Parameters!LANGUAGE.Value = "en-US", "Page " + code.PageNumber().ToString() + " of " + code.TotalPages().ToString(), Parameters!LANGUAGE.Value = "es-MX", "Hoja " + code.PageNumber().ToString() + " de " + code.TotalPages().ToString(), 1 = 1, "Page " +code.PageNumber().ToString() + " of " + code.TotalPages().ToString())