Adenium Obesum - Desert Rose

[Archimedes78]

I got this desert rose this summer at a class and am having a little bit of trouble with it. I don't know it I'm watering it enough or if I need to put a grown lamp on it. It's currently in front of a window that gets decent morning and afternoon light. The picture below is one from this summer when I brought it home.

Right now the tree does have some leaves on it, but it's not flourishing. I tried two grafts on it that failed, so I decided to hold off any trying any others for now. If anyone has some tips/tricks to working with adenium that would be appreciated.

Thanks!