Cubase Sx Midi Issues, problem with midi playback Options

[huwthom]

I've just got cubase sx and i'm having a few problems. I've connected a keyboard through my tascam us 122 and while I can see that the signal is being recorded, I can't hear any playback. Using standard audio channels with guitars etc is no problem, but I can't find a way to make the midi work. It's probably something incredibly simple, but any help would be appreciated.