I may be totally off track here but I've got cubase le as well and kind of had the same problem. What I had to do was go to Devices then VST Instruments then a little box pops with 8 different lines that say No VST Instrument. I selected the first box and it split into two. I then selected my instrument and then the patch (For instance I have a B4 organ). I selected B4 for the instrument and the patch was 'Screamin B4'. I closed that and now the B4 / Screamin B4 patch is loaded. After that I went to the left side of my screen and where it says MIDI 01 it has a little arrow to the side that either points down or up. You have to click the arrow to let the box open up. You will see IN and OUT. Select in: and choose USB audio device. The select OUT: and choose your instrument. Your patch should already be loaded. You will see the patch in the little box that says prg: . That's how it works on mine. I have the M-Audio midi controller. Good luck.