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Pretty simple... it's just not uploading. Downloading like a champ but no uploading. I have DHT and PEX disabled, and I'm on Windows 7.

How many active leechers? Could it be possible that no one wants the file you're seeding?
Are you seeding from a torrent that has multiple seeders/seedboxes? You're not getting a chance to upload because the fast seeders or seedboxes are way too fast for you to get a chance. Private torrent sites almost always use at least one dedicated seedbox.
In general, you should enable DHT and PEX both of which is likely to give you more upload opportunity, unless you're talking private torrent sites... then there's almost no hope (see section about seedboxes).

Hmmmm I suppose it's possible that there's just no one downloading it (the peers all say "0(some number)". What does that mean? What's the number in brackets?) but I used to get some upload on uTorrent... but on this I think I'm getting literally 0 upload.

Actually... that's what I thought but I've just put on the "ratio" column and some of the numbers aren't 0, so I guess I must be uploading SOMETHING. Still seems like a lot less, but I dunno.

Number in brackets means you cannot connect to them for various reasons.
Are you (green light) connected? Forwarded port through router/firewall, or successfully using upnp?

Ah, well, the thing isn't green - it's yellow. But I don't understand why. I had it on the default port and it was a green but I wanted to try switching ports so I did but I also forwarded the port, but for some reason it's still yellow. What's the default port? This error was before I messed this up but I guess maybe it was just temporary and this is now the problem?