Mobile devices & DJ apps

When I connect a Pacemaker with its power on to the CDJ-900 by USB then turn on the CDJ's power, the Pacemaker is not recognized.

The Pacemaker is designed to be recognized when it is connected with the CDJ-900's power turned on. When using a Pacemaker, be sure to turn the CDJ-900's power on before connecting the Pacemaker.