I have downloaded two torrents but I can't find them in download directory, they are in cache directory, they are completed and I am seeding them, it happened once some weeks ago with partial downloaded torrent (selected files), I always use last svn snapshot

Cache directory is symlink to where your files are downloaded. Are you sure you're looking into right downloads directory?
Check where do those symlinks point to.

oh, it has been downloaded to default directory and so that's why I did not find them, thanks, I feel so lame