I have used GPO4 for the past year with Sibelius 6.2 and recently bought Pro Tools 9. My first installation of GPO4 did not include RTAS, but now I need to reinstall GPO4 WITH RTAS in order to put sound to the Pro Tools incoming midi files. Every time I try to reinstall GPO4 with RTAS, however, I get an "Error 5" message - "Not authorized". Try as I might, I can't seem to get RTAS installed. Is there a specific set of instructions for reinstalling GPO4 with RTAS, or is there another way to do this that I'm not aware of? Thanks.