I'm not sure I follow you, my english is not as good as I would want it to be.
I just made a clean install of my OS so I'm recetting my midi keybord, so I will do it and
put every thing I did here.
First I install the interface driver that I got from there web site (to have the most up to date one).
I use an Edirol US-1S (1 in, 1 out).
After install I open audio midi setup, in midi I see my interface, but not my keybord.
I add periferic?? (ajouter périférique).
It made appear an keybord desingned icon, I double click it to edit it.
(I just put name and model, for simple use you don't need more edit)
Look over the icon there is arrow sape desing they represent the in and the out.
Plug them as you would plug a normal midi cable (out goes in in, and in goes in out)
After that test cofig like I mention I my other post it should work.
(When you play on your keybord in test config. mode the computer should make
noice for each note you press)
If it don't work look if you got the cable plug right.
I put tape on one cable so I don't confuse them.