You have to send a message once to enable 'remote sysex'.

This message is F0 10 06 05 F7

Note: the Matrix1000 has some bugs...
Read more here: http://wolzow.mindworks.ee/analog/m1k-firmware.htm

Be careful no to send sysex messages to fast or you will crash the Matrix... Even if MIDI bauds are always the same, today midi port buffers are a lot faster than in the 80's ;)

Have fun