you need to set the position of the camera... more than likely you are spawning the camera in the ground at (0,0,0)
try this or some variation:
camera=framework.main.camera
camera:SetPosition(Vec3(0,3,-2))
as far as the null... not sure... i took this code and and placed it into the root of my game directory and changed the abstractpath to "". Changed the name of the scene to my scene and then dragged and dropped the lua script onto the Engine.EXE and it worked just fine after I positioned the camera...
this could be an issue with the slashes... i think its supposed to be a forward slash in the abstractpath not a backward slash... but I never hardcode my paths, so I am not sure...