Three.js: Different lighting effect on different computer doing Multiple lights enviroment
===

I am using Three.js to do a multiple lights environment. I add 4 directional lights and 1 ambient light. It works great from my windows 7+Chrome+fireworks computer, also another Mac desktop and a Macbook pro. But when I use another laptop to test it doesn't work. The laptop use same Windows 7 64-bits system and same chrome and fireworks. But there is no lights at all at that laptop. Does anybody know what's the problem?  