You apparently installed MBX V5 as an upgrade from 4. That installation deactivated the dongle, so it will no longer work. MBX V5 works with a "software" dongle that is code-based. You should have a separate CD to register the code number in the MBX V5 box. If you've already done 2 installs then you'll need Janome help to "unregister" your previous installations.