DJS sound is not output.

[DJ Play function] One sound card is by default assigned to each of the two mixer outputs. If this setting is changed, no sound card may have been assigned to the master output of the mixer. If so, headphone CUE must be on or no sound will be output. Check the mixer/sound card settings. --> See Section 9-4, "Mixer and Sound Card Settings" on page 100 in the User's Manual.