Sounds like you need to see if a) you have a module available for your midi onboard device, and b) if there is, make sure the module is loaded, and if it isn't loaded or compiled, you need to load or compile it.
As you are using alsa, you could use (in a console) the command ALSAMIXER, and see if there is a control(s) on the mixer panel for the midi channel/device, make sure it is activated there.
If you change anything in the mixer, then after you exit, you must use ALSACTL STORE to save the settings.
typing LSMOD in a terminal will tell you what modules you have loaded.
If you don't see one like "alsa_snd_seq" or something like that, then the sequencer is not loaded.
I am not too familiar with Ubuntu-Edgy, but on my system (Slackware) I have a modules-2.6.20 file in my /etc directory, which can be used to load or 'modplug' kernel modules during boot. If such a file exists on your system (in the /etc folder) search it for the needed sequencer module for your device, and uncomment the device line so it will load during boot.
Ubuntu may not have such files, so you will need to skip this step.
If there is a module compiled but not loaded, try typing MODPROBE ALSA_SND_SEQ (for 2.6 kernel) or INSMOD ALSA_SND_SEQ (2.4 kernels) and see if it will load.
As a last resort, I would venture a guess that you may need to enable support for the necessary midi device in the kernel, because it isn't there yet, in which case you would have to custom-config a kernel with the needed support.
It isn't as bad as it sounds, but if this gets you anywhere for starters, please post your findings and someone wll try to help further.