I don't know what happened but the midi kbd works now (even without jack server running). Maybe installing of Jamin added me in Audio group automatically or "apt-get install -f" made some changes.
And recently (before midi-kbd started working) i also installed Windows7 on this notebook, and noticed, that usb3.0 port doesn't work. I installed usb3.0 driver for Windows, and now it works on Win7. Than i ran Linux and plugged the usb cable of midi-kbd in usb3.0. The midi-kbd works in LMMS now, in all the usb ports (3.0 and 2.0).
ok, im sure it will be looked at, but it will help if you tell us all what hw you have and what OS distro aso..
I dont own midiKB, so i have no knowledge, except what is written here https://lmms.io/wiki/index.php?title=Using_MIDI
But you have already read that(?)