A common problem: Remember that a symlink only points to the directory, the symlink itself has all permissions to do anything, but the directory it points to may not, if you have issues using symlinks it is probably a permissions problem with the target directory, be sure to check this.
For Ubuntu users, if your directories and files are on other devices, like /dev/hda1, you must add mpd user to "plugdev" group.
Tohle sis také zkontroloval (je to citát z té wiki)?