We might be on a bit of a wild goose chase now, so bare with me:
1. Are you using the downloaded code
from the book's website?
2. Are you using Eclipse?
3. In Eclipse, select Window > Preferences and click leJOS NXJ on the side. In the field NXJ_HOME it has a directory. Is this the directory you copied the snapshot files into?
4. In this NXJ_HOME directory, if you browse to it in the file explorer, do you see "snapshot" folder in there? You should see only the folders bin, lib, project, and source.
5. Did you try restarting Eclipse, saving the file again and uploading again?