I got the Gimp a few days ago and have been trying to use it to create a map for a campaign I'm working on, and this tutorial is exactly why I came to the Cartographer's Guild. The results I've seen are amazing.

I have run into a problem near the very beginning though. I get as far as creating the land noise layer using the filters->render->clouds->solid noise.
I then set the mode of that layer to overlay...and nothing happens. It doesn't seem to do anything at all to the image. Am I missing a step here?

PS: I'm using Gimp 2.6.6 on Windows XP.