When I first set up my tree, the top row did not light up.  The description said if one light went out the rest would stay lit, but that didn't happen.  I called the company from the tree maker and they had me take out a couple bulbs and replace them with new ones, which I did.  The row then lit up.  I'm still concerned it might go out again and why the whole row went out when it wasn't supposed to.  However, it was really easy to set it up.  Now it's my boys turn to decorate it and we'll have to see how it looks after they are done to see how well it fills out.