why does world background appear very dark when rendered? I was getting a perfectly blue and white cloudy colourful background but somehow it seems all darkened, I must've change some settings unintentionally, but I can't figure our how to put it back normal. can you please help me?
here is a screen shot from my render

dark background



normal background which I want it back :)


blender file
I'm using cycles with pro skies add-on
It looks like you might have set the clamp settings set too low.
Try increasing them until you find a good balance between highlights and fireflies (I typically use something like 2, but you might be able to get away with 1). 

You can probably leave Clamp Direct at 0, since direct bounces typically don't result in fireflies.