i have it on os x, it has rendered before after reinstalling it has not rendered 
leopard is this specific os
Have you made sure that the path for the luxrender executable is correct? (In the blender exporting script thingy)
that should be correct. I think i have one file in incorrect folder, should be in bin folder but i have my
computer in finnish, i am not sure what bin is in finnish, got to check and try again…