I'm having the same 'not seeding' situation..  I completed download and left Transmission (on Mac pro) on for days..  When I check my seeding stats.  the server says it is seeding, but i guess nobody is downloading..  I can leach and seed on any number of sights,,Anounamouse, Kickass Torrents, mac torrents, pirate bay, etc.

Any instructions for Transmission would be helpful..I couldn't find any.

thanx  angelonyc