I think it is because of the way the tracker counts "downloading torrents:" If you have downloaded a torrent with many files, and you have only selected some of them to download, your torrent client may show this torrent as 100% completed. But, the gt.ru tracker sees this as only partially downloaded, and this torrent will count it as one of your 15 allowed downloading torrents. I sometimes have the same problem.
The way I fix this is to look at older torrents that I have downloaded this way (only some of the files, not all) that also have very few seeders (so I won't be uploading much to them). I then delete the torrent, but keep the files (if I want), and then it won't count against the allowed maximum. It might take a few minutes for the gt.ru tracker to recognise this and update your total.
I hope this helps your situation. Bonne chance!