Can you post a screen shot of what's going on with the mask? Your shot without the mask looks like you have a gradient of white to transparent, as you're seeing part of the image. So if you have white to transparent on a white mask, it's not going to do anything. You need white to black.
I have the white to black gradient selected, but it doesn't appear on the mask. The mask is obviously present since I was able to draw on the right portion of the photo, but the gradient doesn't appear. As far as I'm aware, the other screenshot was done witht the white to black gradient as well, but I may be wrong on that.