I don't understand the description, maybe a screen shot would help.
Does the SPL meter work?
Can you make measurements?
Have you used REW successfully to do anything else?
Has anything been captured in the log files? They are in a folder called REW in the user library folder, which no longer appears in Finder by default. To display it either browse to ~/Library/Logs or open your Home folder in Finder (Shift Command + H), select View > Show View Options then select the checkbox to show the library folder.