And you have a carbonite.toc file inside that carbonite folder ?
The folder structure for any addon should be as follows:
World of Warcraft / Interface / Addons / <AddonName> / <AddonName>.toc
Now if that is still the case with you then the next question to ask is how many versions of wow have you got installed. On Vista and Windows 7 machines The Burning Crusade and more specifically the Lich King expansion asked to move the wow folder to a more secure location ( Users/Public/Games ). However, it doesn't move it but just copies it and thus you end up with 2 game folders. If that is the case look in the extra folder and see if the carbonite in there as well and if not try copying it there too.