it's not a config problem. it's a had passkey problem..
the paskey is based on the hash is generated...
if it's not auto generated for every refresh of the upload.php page.. then there is your problem..
I too have the same problem and working on it for 3 days... and still haven't figured it out...
the solution lies in announce.php, download.php ( which seems to be ok).. the download is ok.. upload.php and the mysql tables and the querry
problem long solved...