I did everything right uploading the torrent. Re-downloaded the small torrent file, my torrent app (FOLX) checked the files and put it in the seeding queue. But my torrents became dead nearly immediately. What's the problem?

Ok, I created a torrent file, then uploaded and filled everything to the Upload page.
Then I re-download the recently uploaded torrent file and launch it to start seeding. But the torrent program (Folx) doesn't start checking the folder with files to start seeding.
What's the problem? Could you help me please??

@bernd Thanks! That helped.
Now it is said that I have to re-download the torrent to make it visible. What do they mean? To re-download what from where?

Is there any alternative torrent maker on Mac? Or what's the problem?
It's said Upload failed, Dictionary is missing key(s).

The uploading guide on the site is missing also so I did it by myself.