My experience with MIDISport is that the driver may have to be installed more than once and the installation has a specific sequence of event, i.e., start installation software with device attached, unattached device, continue with software install, connect device, etc. Further, the MIDIsport must be used in the same port which was used at the time of installation. The MIDISport will not be recognized if you install using one port then later connect it in a different port.
If the above does not apply, please forgive the nuisance.
Kind regards,
Living Room Rocker