Hey xiaozhes,
It looks like your lights are working fine. What’s causing this lighting issue is material on your floor. texture you have plugged in as your Normal is not actually a normal map, and removing it seems to fix problem.
You might need to look into creating a normal map using a different method than whatever you used first time. Here’s a tutorial I found that mentions a couple different programs that can help you create a normal map from your texture:
Hope that helps!