problems using many spotlights on one face

Hi,

I am having a problem with lighting in Unity pro. I am working on a virtual exhibition where I have a few photographs on each wall. What I want to do is to light up the photographs with spotlights. Now the problem I am having is that every time I put more than one spotlight on each wall it seems to affect the other spotlights on that same wall by ether turning it off or the whole wall is light up. Ive tried to change the settings on the spotlight, like the intensity, but it does not seem to change anything. Any ideas what might be causing this problem? Is it not possible to have more than one spotlight per face?