If this is what i'm thinking, i didn't have very much luck with it either. What i was trying to do is have my (old school) album browser to display the ghraphic of a folder when the music folder didn't have album art to display. I thought it would pick it up by just droping a gif in the skin folder but that didn't work; so i put the same gif in RR's folder and still nothing (it displays some other default folder image). The last thing i was going to try was to list the gif in the third line of the .skin file but i haven't got around to trying it.
If this is not your problem..disregard.