I went further :
to upgrade the Dynamixel to the good version (36 for MX-28 or 64), download the Roboplus 1.1.3
http://en.robotis.com/BlueAD/board.php?bbs_id=downloads&mode=view&bbs_no=1132559&page=2&key=&keyword=&sort=&scate=SOFTWARE
BUT DO NOT UPGRADE IF YOU ARE PROPOSED TO !!