Hey,
the ddm4000 has MIDI right but no MIDI usb interface. You have to get an midi-USB-Interface and connect it to the MIDI out of the mixer.
Your mixer has only MIDI IN and OUT connectors at the back of the Mixer panel so you need somthing like this:
http://www.thomann.de/gb/maudio_midisport_uno.htmto get MIDI to the computer.
regards
Christian