Hey Deejaytshi,

Try going to Utilities>Audio Midi>once open, go to the task bar at top of Mac screen and window>Midi window. This should show you the midi devices installed/connected to your computer.

Do you see the Vestax VCI-100 there?
You may see an icon there that is highlighted when the Vestax VCI-100 is connected but doesn't say Vestax VCI-100. Whatever the Vestax VCI-100 is registering as you should disconnect your Vestax VCI-100 and delete that icon then re-connect it. See if it then shows up. After you have done this try re-opening DJ Intro. Does it show up?

If not try reinstalling DJ Intro with the controller connected.

Regards
Dave W