Please try that if it is being detected on Windows open the disk management and check the file system the drive is using.
Instructions for Winodws can be found here.
You can also check on the Mac disk utility if the drive appears in there and the file system that is using.
Instructions here: http://wdc.custhelp.com/app/answers/detail/a_id/1362/session/L2F2LzEvc25vLzEvdGltZS8xMzY1MTgxNzE4L3NpZC90SzY1NVptbA%3D%3D
