http://www.gnutellaforums.com/genera...tml#post316433

Could be a permissions error. Are you admin of your computer? Do a Safe reboot and repair permissions.

BTW Mac iTunes will not add these files -> mp3Pro, ogg vorbis, Real, WMV, as the main ones. It will generally also not add a file it already has in its library (though this may have changed with more recent iTunes versions.) It may not add a file that is corrupt.

Go to iTunes menu bar, File -> Add .. and direct it to the LW download folder, choose the song you wish to add. If it doesn't add, then something is wrong with the file or you already have it in the library or non compatible format or a iTunes Music Library permissions error.
Make sure both your iTunes music library and LW download folder you have similar permissions for. Both should belong to your account as user.