Hiya!
First concerning the -relight option, it can take a really really long time to relight a map. An hour, perhaps several. That's why you shouldn't start PS with -relight all the time, but do it once and then remove the command.
If that doesn't help, you can try adding -fullbright instead of relight. It eliminates shadows, and therefore has a chance of helping. My guess though would be that -relight will do the trick if you let it finish :]