Hi

This usually means that the host is not allowing uploads, has too little bandwidth available or already has the full crew of downloaders and queuers in place. Only in the last situation is it worth trying again later. The first two are the more common (there are a lot of freeloaders around who only want to take and not give) so mostly there is nothing that can be done except keep the desired tracks on your want list and keep trying. Sonner or later an alternative source will turn up unless what you seek is excessively rare.