Impossible to reconnect Ubuntu One after remove credentials for the machine on the web

[Antoine Morit]

I'm using with great satisfaction Ubuntu One on my Dell XPS13, on ubuntu 13.10 from a long time.
Yesterday, I have remove (by error) my credentials for my system on the web, from my ubuntu one account.
Since I made this error, ubuntu one was no longer active (I understand why...).
The problem is that I cannot configure it aigain.
I tried to uninstall and reinstall following these instructions : https://one.ubuntu.com/help/faq/how-do-i-completely-remove-and-reinstall-ubuntu-one (after removing keys ubuntu with seahorse), and it's always the same : "Credential error", and no more message, when I try to connect my account.
My account is OK, and works perfectly with my android device, but I have no more syncs...
Is it a bug ? Or did I make an error while tying to reinstall cleanly ?